Export the global variable 'ppc_tb_freq', so that modules (like the Book-E
watchdog driver) can use it. To maintain consistency, ppc_proc_freq is
changed to a GPL-only export. This is okay, because any module that needs
this symbol should be an actual Linux driver, which must be GPL-licensed.
Signed-off-by: Timur Tabi <timur@freescale.com>
Acked-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
The following commit broke 83xx because it assumed the 83xx platforms
exposed the "IMMR" address in BAR0 like the 85xx/86xx/QoriQ devices do:
commit 3da34aae03
Author: Kumar Gala <galak@kernel.crashing.org>
Date: Tue May 12 15:51:56 2009 -0500
powerpc/fsl: Support unique MSI addresses per PCIe Root Complex
However that is not true, so we have to search through the inbound
window settings on 83xx to find which one matches the IMMR address to
determine its PCI address.
Reported-by: Ilya Yanok <yanok@emcraft.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Replace EXTRA_CFLAGS with ccflags-y and EXTRA_AFLAGS with asflags-y.
Signed-off-by: matt mooney <mfm@muteddisk.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The default for llseek is changing, so we need
explicit operations everywhere.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Jeremy Kerr <jk@ozlabs.org>
Cc: linuxppc-dev@ozlabs.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Current firmware only allows us to send IRQs to the first processor or
all processors. We currently check to see if the passed in mask is equal
to the all_mask, but the firmware is only considering whether the
request is for the equivalent of the possible_mask. Thus, we think the
request is for some subset of CPUs and only assign IRQs to the first CPU
(on systems without irqbalance running) as evidenced by
/proc/interrupts. By using possible_mask instead, we account for this
and proper interleaving of interrupts occurs.
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Use set_dma_ops and remove unused oddly-named temp pointer sd.
Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
While looking at some code paths I came across this code that zeros
memory then copies over the entire length.
Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Release the TCE table as the XXX suggests, except on FW_FEATURE_ISERIES,
where the tables are allocated globally and reused.
Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The kernel doc for device_register (and device_initialize) very clearly
state to call put_device not kfree after calling, even on error.
Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The current check is wrong because it does not take the DMA offset intot
account, and in the case of a driver which doesn't actually support
64bits would falsely report that device as working.
Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The table offset is in entries, each of which imply a dma address of
an IOMMU page.
Also, we should check the device can reach the whole IOMMU table.
Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
BUID_HI and BUID_LO are used to pass data to call_rtas, which expects
ints or u32s. But the macro doesn't cast the return, so the result is
still u64. Use the upper_32_bits and lower_32_bits macros that have been
added to kernel.h.
Found by getting printf format errors trying to debug print the args, no
actual code change for 64 bit kernels where the macros are actually
used.
Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Acked-by: Linas Vepstas <linasvepstas@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
In this case, a device_node structure is stored in another structure that
is then freed without first decrementing the reference count of the
device_node structure.
The semantic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)
// <smpl>
@r exists@
expression x;
identifier f;
position p1,p2;
@@
x@p1->f = \(of_find_node_by_path\|of_find_node_by_name\|of_find_node_by_phandle\|of_get_parent\|of_get_next_parent\|of_get_next_child\|of_find_compatible_node\|of_match_node\|of_find_node_by_type\|of_find_node_with_property\|of_find_matching_node\|of_parse_phandle\|of_node_get\)(...);
... when != of_node_put(x)
kfree@p2(x)
@script:python@
p1 << r.p1;
p2 << r.p2;
@@
cocci.print_main("call",p1)
cocci.print_secs("free",p2)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Joe Perches <joe@perches.com>
Reviewed-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Enable partition migration in the kernel. To do this a new sysfs file,
/sys/kernel/mobility/migration, is created. In order to initiate a migration
the stream id (generated by the HMC managing the system) is written to this
file.
After a migration occurs, and what is the majority of this code, the device
tree needs to be updated for the new system the partition is running on. This
is done via the ibm,update-nodes and ibm,update-properties rtas calls which
return information regarding which nodes and properties of the device tree
are to be added/removed/updated.
Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Export the rtas_ibm_suspend_me() routine. This is needed to perform
partition migration in the kernel.
Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Export routines associated with adding and removing device tree nodes on
pseries needed for device tree updating.
Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
arch/powerpc/platforms/built-in.o:(.toc1+0x18): undefined reference to `__early_start'
This is due to the 85xx/smp.c not handling the 64-bit side properly. We
need to set the entry point for secondary cores on ppc64e to
generic_secondary_smp_init instead of __early_start that we due on ppc32.
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Since powerpc uses -Werror on arch powerpc, the build was broken like
this:
cc1: warnings being treated as errors
arch/powerpc/kernel/module.c: In function 'module_finalize':
arch/powerpc/kernel/module.c:66: error: unused variable 'err'
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With all the recent module loading cleanups, we've minimized the code
that sits under module_mutex, fixing various deadlocks and making it
possible to do most of the module loading in parallel.
However, that whole conversion totally missed the rather obscure code
that adds a new module to the list for BUG() handling. That code was
doubly obscure because (a) the code itself lives in lib/bugs.c (for
dubious reasons) and (b) it gets called from the architecture-specific
"module_finalize()" rather than from generic code.
Calling it from arch-specific code makes no sense what-so-ever to begin
with, and is now actively wrong since that code isn't protected by the
module loading lock any more.
So this commit moves the "module_bug_{finalize,cleanup}()" calls away
from the arch-specific code, and into the generic code - and in the
process protects it with the module_mutex so that the list operations
are now safe.
Future fixups:
- move the module list handling code into kernel/module.c where it
belongs.
- get rid of 'module_bug_list' and just use the regular list of modules
(called 'modules' - imagine that) that we already create and maintain
for other reasons.
Reported-and-tested-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Adrian Bunk <bunk@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The logic to distinguish marked instruction events from ordinary events
on PPC970 and derivatives was flawed. The result is that instruction
sampling didn't get enabled in the PMU for some marked instruction
events, so they would never trigger. This fixes it by adding the
appropriate break statements in the switch statement.
Reported-by: David Binderman <dcb314@hotmail.com>
Cc: stable@kernel.org
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Make sigreturn zero regs->trap, make do_signal() do the same on all
paths. As it is, signal interrupting e.g. read() from fd 512 (==
ERESTARTSYS) with another signal getting unblocked when the first
handler finishes will lead to restart one insn earlier than it ought
to. Same for multiple signals with in-kernel handlers interrupting
that sucker at the same time. Same for multiple signals of any kind
interrupting that sucker on 64bit...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
compat_alloc_user_space() expects the caller to independently call
access_ok() to verify the returned area. A missing call could
introduce problems on some architectures.
This patch incorporates the access_ok() check into
compat_alloc_user_space() and also adds a sanity check on the length.
The existing compat_alloc_user_space() implementations are renamed
arch_compat_alloc_user_space() and are used as part of the
implementation of the new global function.
This patch assumes NULL will cause __get_user()/__put_user() to either
fail or access userspace on all architectures. This should be
followed by checking the return value of compat_access_user_space()
for NULL in the callers, at which time the access_ok() in the callers
can also be removed.
Reported-by: Ben Hawkes <hawkes@sota.gen.nz>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Tony Luck <tony.luck@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: James Bottomley <jejb@parisc-linux.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: <stable@kernel.org>
The slab.h header is required to use the kmalloc() family of functions.
Due to recent kernel changes, this header must be directly included by
code that calls into the memory allocator.
Without this patch, any code which includes this header fails to build.
Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tighten up time timing around the gpio reset functionality. Add a 200ns
delay before remuxing the pins back to ac97 to comply with the ac97 spec.
Signed-off-by: Eric Millbrandt <emillbrandt@dekaresearch.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This function is implemented as though the function of_get_next_child does
not increment the reference count of its result, but actually it does.
Thus the patch adds of_node_put in error handling code and drops a call to
of_node_get.
The semantic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)
// <smpl>
@r exists@
local idexpression x;
expression E1;
position p1,p2;
@@
x@p1 = of_get_next_child(...);
... when != x = E1
of_node_get@p2(x)
@script:python@
p1 << r.p1;
p2 << r.p2;
@@
cocci.print_main("call",p1)
cocci.print_secs("get",p2)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Replace the BOOK3S_64 specific mtmsrd with the generic MTMSRD macro.
Only enable ldstfp when CONFIG_PPC_FPU is set.
Signed-off-by: Sean MacLennan <smaclennan@pikatech.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
arch/powerpc/mm/mmu_context_nohash.c assumes the boot cpu
will always have smp_processor_id() == 0. This patch fixes
that assumption
Signed-off-by: Matthew McClintock <msm@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This patch wires up the various socket system calls on PowerPC so that
userspace can call them directly, rather than by going through the
multiplexed socketcall system call.
Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Add a call to of_node_put in the error handling code following a call to
of_find_node_by_type.
The semantic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)
// <smpl>
@r exists@
local idexpression x;
expression E,E1,E2;
statement S;
@@
*x =
(of_find_node_by_path
|of_find_node_by_name
|of_find_node_by_phandle
|of_get_parent
|of_get_next_parent
|of_get_next_child
|of_find_compatible_node
|of_match_node
|of_find_node_by_type
|of_find_node_with_property
|of_find_matching_node
|of_parse_phandle
)(...);
...
if (x == NULL) S
<... when != x = E
*if (...) {
... when != of_node_put(x)
when != if (...) { ... of_node_put(x); ... }
(
return <+...x...+>;
|
* return ...;
)
}
...>
(
E2 = x;
|
of_node_put(x);
)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Add calls to of_node_put in the error handling code following calls to
of_find_node_by_path and of_find_node_by_phandle.
The semantic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)
// <smpl>
@r exists@
local idexpression x;
expression E,E1;
statement S;
@@
*x =
(of_find_node_by_path
|of_find_node_by_name
|of_find_node_by_phandle
|of_get_parent
|of_get_next_parent
|of_get_next_child
|of_find_compatible_node
|of_match_node
)(...);
...
if (x == NULL) S
<... when != x = E
*if (...) {
... when != of_node_put(x)
when != if (...) { ... of_node_put(x); ... }
(
return <+...x...+>;
|
* return ...;
)
}
...>
of_node_put(x);
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Add a call to of_node_put in the error handling code following a call to
of_find_node_by_phandle.
The semantic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)
// <smpl>
@r exists@
local idexpression x;
expression E,E1;
statement S;
@@
*x =
(of_find_node_by_path
|of_find_node_by_name
|of_find_node_by_phandle
|of_get_parent
|of_get_next_parent
|of_get_next_child
|of_find_compatible_node
|of_match_node
)(...);
...
if (x == NULL) S
<... when != x = E
*if (...) {
... when != of_node_put(x)
when != if (...) { ... of_node_put(x); ... }
(
return <+...x...+>;
|
* return ...;
)
}
...>
of_node_put(x);
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Add a call to of_node_put in the error handling code following a call to
of_find_node_by_path.
The semantic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)
// <smpl>
@r exists@
local idexpression x;
expression E,E1;
statement S;
@@
*x =
(of_find_node_by_path
|of_find_node_by_name
|of_find_node_by_phandle
|of_get_parent
|of_get_next_parent
|of_get_next_child
|of_find_compatible_node
|of_match_node
)(...);
...
if (x == NULL) S
<... when != x = E
*if (...) {
... when != of_node_put(x)
when != if (...) { ... of_node_put(x); ... }
(
return <+...x...+>;
|
* return ...;
)
}
...>
of_node_put(x);
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The PCI-Express bus off the U4/CPC945 bridge supports direct DMA to
all of memory, bypassing the DART iommu, for 64-bit capable devices.
This adds support for it on Bimini and Apple Quad G5's in order to
improve DMA performances of cards using that slot (the x16 graphics
slot). Tested with an Intel ixgbe 10GE card.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Some platforms may want to override dma_set_mask() to take into
account some specific "features" such as the availability of
a direct-map window in addition to an iommu.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This patch removes all explicit tests for the TIF_32BIT flag
Signed-off-by: Denis Kirjanov <dkirjanov@kernel.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Neither lfs nor stfs touch the fpscr, so remove the restore/save of it
around them.
Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Since the cpu accounting code uses the hypervisor dispatch trace log
now when CONFIG_VIRT_CPU_ACCOUNTING = y, the previous commit disabled
access to it via files in the /sys/kernel/debug/powerpc/dtl/ directory
in that case. This restores those files.
To do this, we now have a hook that the cpu accounting code will call
as it processes each entry from the hypervisor dispatch trace log.
The code in dtl.c now uses that to fill up its ring buffer, rather
than having the hypervisor fill the ring buffer directly.
This also fixes dtl_file_read() to handle overflow conditions a bit
better and adds a spinlock to ensure that race conditions (multiple
processes opening or reading the file concurrently) are handled
correctly.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Currently, when CONFIG_VIRT_CPU_ACCOUNTING is enabled, we use the
PURR register for measuring the user and system time used by
processes, as well as other related times such as hardirq and
softirq times. This turns out to be quite confusing for users
because it means that a program will often be measured as taking
less time when run on a multi-threaded processor (SMT2 or SMT4 mode)
than it does when run on a single-threaded processor (ST mode), even
though the program takes longer to finish. The discrepancy is
accounted for as stolen time, which is also confusing, particularly
when there are no other partitions running.
This changes the accounting to use the timebase instead, meaning that
the reported user and system times are the actual number of real-time
seconds that the program was executing on the processor thread,
regardless of which SMT mode the processor is in. Thus a program will
generally show greater user and system times when run on a
multi-threaded processor than on a single-threaded processor.
On pSeries systems on POWER5 or later processors, we measure the
stolen time (time when this partition wasn't running) using the
hypervisor dispatch trace log. We check for new entries in the
log on every entry from user mode and on every transition from
kernel process context to soft or hard IRQ context (i.e. when
account_system_vtime() gets called). So that we can correctly
distinguish time stolen from user time and time stolen from system
time, without having to check the log on every exit to user mode,
we store separate timestamps for exit to user mode and entry from
user mode.
On systems that have a SPURR (POWER6 and POWER7), we read the SPURR
in account_system_vtime() (as before), and then apportion the SPURR
ticks since the last time we read it between scaled user time and
scaled system time according to the relative proportions of user
time and system time over the same interval. This avoids having to
read the SPURR on every kernel entry and exit. On systems that have
PURR but not SPURR (i.e., POWER5), we do the same using the PURR
rather than the SPURR.
This disables the DTL user interface in /sys/debug/kernel/powerpc/dtl
for now since it conflicts with the use of the dispatch trace log
by the time accounting code.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This arranges for the lppaca structs for most cpus to be dynamically
allocated in the same manner as the paca structs. If we don't include
support for legacy iSeries, only the first lppaca is statically
allocated; the rest are dynamically allocated. If we include legacy
iSeries support, then we statically allocate the first 64 lppaca
structs, since the iSeries hypervisor requires that the lppaca
structs be present in the data section of the kernel image, but
legacy iSeries supports at most 64 cpus.
With CONFIG_NR_CPUS, the kernel image size for a typical pSeries config
went from:
text data bss dec hex filename
9524478 4734564 8469944 22728986 15ad11a ../test-1024/vmlinux
to:
text data bss dec hex filename
9524482 3751508 8469944 21745934 14bd10e ../test-1024/vmlinux
a reduction of 983052 bytes overall.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Currently we have the lppaca structs as a simple array of NR_CPUS
entries, taking up space in the data section of the kernel image.
In future we would like to allocate them dynamically, so this
abstracts out the accesses to the array, making it easier to
change how we locate the lppaca for a given cpu in future.
Specifically, lppaca[cpu] changes to lppaca_of(cpu).
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Simple cleanup by moving arch_sd_sibling_asym_packing from process.c to
smp.c to save an #ifdef CONFIG_SMP
No functionality change.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Add a check for the stack canary when we oops, similar to x86. This should make
it clear that we overran our stack:
Unable to handle kernel paging request for data at address 0x24652f63700ac689
Faulting instruction address: 0xc000000000063d24
Thread overran stack, or stack corrupted
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The POWER architecture does not require stcx to check that it is operating
on the same address as the larx. This means it is possible for an
an exception handler to execute a larx, get a reservation, decide
not to do the stcx and then return back with an active reservation. If the
interrupted code was in the middle of a larx/stcx sequence the stcx could
incorrectly succeed.
All recent POWER CPUs check the address before letting the stcx succeed
so we can create a CPU feature and nop it out. As Ben suggested, we can
only do this in our syscall path because there is a remote possibility
some kernel code gets interrupted by an exception that ends up operating
on the same cacheline.
Thanks to Paul Mackerras and Derek Williams for the idea.
To test this I used a very simple null syscall (actually getppid) testcase
at http://ozlabs.org/~anton/junkcode/null_syscall.c
I tested against 2.6.35-git10 with the following changes against the
pseries_defconfig:
CONFIG_VIRT_CPU_ACCOUNTING=n
CONFIG_AUDIT=n
CONFIG_PPC_4K_PAGES=n
CONFIG_PPC_64K_PAGES=y
CONFIG_FORCE_MAX_ZONEORDER=9
CONFIG_PPC_SUBPAGE_PROT=n
CONFIG_FUNCTION_TRACER=n
CONFIG_FUNCTION_GRAPH_TRACER=n
CONFIG_IRQSOFF_TRACER=n
CONFIG_STACK_TRACER=n
to remove the overhead of virtual CPU accounting, syscall auditing and
the ftrace mcount tracers. 64kB pages were enabled to minimise TLB misses.
POWER6: +8.2%
POWER7: +7.0%
Another suggestion was to use a larx to something in the L1 instead of a stcx.
This was almost as fast as removing the larx on POWER6, but only 3.5% faster
on POWER7. We can use this to speed up the reservation clear in our
exception exit code.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This adds the equivalent of csum_and_copy_from_user for the receive side so we
can copy and checksum in one pass. It is modelled on the generic checksum
routine.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
We use the same core loop as the new csum_partial, adding in the
stores and exception handling code. To keep things simple we do all the
exception fixup in csum_and_copy_from_user. This wrapper function is
modelled on the generic checksum code and is careful to always calculate
a complete checksum even if we only copied part of the data to userspace.
To test this I forced checksumming on over loopback and ran socklib (a
simple TCP benchmark). On a POWER6 575 throughput improved by 19% with
this patch. If I forced both the sender and receiver onto the same cpu
(with the hope of shifting the benchmark from being cache bandwidth limited
to cpu limited), adding this patch improved performance by 55%
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
