Currently ext3_get_block() only maps or allocates one block at a time. This
is quite inefficient for sequential IO workload.
I have posted a early implements a simply multiple block map and allocation
with current ext3. The basic idea is allocating the 1st block in the existing
way, and attempting to allocate the next adjacent blocks on a best effort
basis. More description about the implementation could be found here:
http://marc.theaimsgroup.com/?l=ext2-devel&m=112162230003522&w=2
The following the latest version of the patch: break the original patch into 5
patches, re-worked some logicals, and fixed some bugs. The break ups are:
[patch 1] Adding map multiple blocks at a time in ext3_get_blocks()
[patch 2] Extend ext3_get_blocks() to support multiple block allocation
[patch 3] Implement multiple block allocation in ext3-try-to-allocate
(called via ext3_new_block()).
[patch 4] Proper accounting updates in ext3_new_blocks()
[patch 5] Adjust reservation window size properly (by the given number
of blocks to allocate) before block allocation to increase the
possibility of allocating multiple blocks in a single call.
Tests done so far includes fsx,tiobench and dbench. The following numbers
collected from Direct IO tests (1G file creation/read) shows the system time
have been greatly reduced (more than 50% on my 8 cpu system) with the patches.
1G file DIO write:
2.6.15 2.6.15+patches
real 0m31.275s 0m31.161s
user 0m0.000s 0m0.000s
sys 0m3.384s 0m0.564s
1G file DIO read:
2.6.15 2.6.15+patches
real 0m30.733s 0m30.624s
user 0m0.000s 0m0.004s
sys 0m0.748s 0m0.380s
Some previous test we did on buffered IO with using multiple blocks allocation
and delayed allocation shows noticeable improvement on throughput and system
time.
This patch:
Add support of mapping multiple blocks in one call.
This is useful for DIO reads and re-writes (where blocks are already
allocated), also is in line with Christoph's proposal of using getblocks() in
mpage_readpage() or mpage_readpages().
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Linus points out that ext3_readdir's readahead only cuts in when
ext3_readdir() is operating at the very start of the directory. So for large
directories we end up performing no readahead at all and we suck.
So take it all out and use the core VM's page_cache_readahead(). This means
that ext3 directory reads will use all of readahead's dynamic sizing goop.
Note that we're using the directory's filp->f_ra to hold the readahead state,
but readahead is actually being performed against the underlying blockdev's
address_space. Fortunately the readahead code is all set up to handle this.
Tested with printk. It works. I was struggling to find a real workload which
actually cared.
(The patch also exports page_cache_readahead() to GPL modules)
Cc: "Stephen C. Tweedie" <sct@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
If /etc/mtab is a regular file all of the mount options (of a file system)
are written to /etc/mtab by the mount command. The quota tools look there
for the quota strings for their operation. If, however, /etc/mtab is a
symlink to /proc/mounts (a "good thing" in some environments) the tools
don't write anything - they assume the kernel will take care of things.
While the quota options are sent down to the kernel via the mount system
call and the file system codes handle them properly unfortunately there is
no code to echo the quota strings into /proc/mounts and the quota tools
fail in the symlink case.
The attached patchs modify the EXT[2|3] and JFS codes to add the necessary
hooks. The show_options function of each file system in these patches
currently deal with only those things that seemed related to quotas;
especially in the EXT3 case more can be done (later?).
Jan Kara also noted the difficulty in moving these changes above the FS
codes responding similarly to myself to Andrew's comment about possible
VFS migration. Issue summary:
- FS codes have to process the entire string of options anyway.
- Only FS codes that use quotas must have a show_options function (for
quotas to work properly) however quotas are only used in a small number
of FS.
- Since most of the quota using FS support other options these FS codes
should have the a show_options function to show those options - and the
quota echoing becomes virtually negligible.
Based on feedback I have modified my patches from the original:
JFS a missing patch has been restored to the posting
EXT[2|3] and JFS always use the show_options function
- Each FS has at least one FS specific option displayed
- QUOTA output is under a CONFIG_QUOTA ifdef
- a follow-on patch will add a multitude of options for each FS
EXT[2|3] and JFS "quota" is treated as "usrquota"
EXT3 journalled data check for journalled quota removed
EXT[2|3] mount when quota specified but not compiled in
- no changes from my original patch. I tested the patch and the codes
warn but
- still mount. With all due respection I believe the comments
otherwise were a
- misread of the patch. Please reread/test and comment. XFS patch
removed - the XFS team already made the necessary changes EXT3 mixing
old and new quotas are handled differently (not purely exclusive)
- if old and new quotas for the same type are used together the old
type is silently depricated for compatability (e.g. usrquota and
usrjquota)
- mixing of old and new quotas is an error (e.g. usrjquota and
grpquota)
Signed-off-by: Mark Bellon <mbellon@mvista.com>
Acked-by: Dave Kleikamp <shaggy@austin.ibm.com>
Cc: Jan Kara <jack@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Fix a problem with ext3 mount option parsing. When remount of a filesystem
fails, old options are now restored.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Use improved credits estimates for quota operations. Also reserve a space
for a quota operation in a transaction only if filesystem was mounted with
some quota options.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
