AcoSail/kernel_optimize_test
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Merge branch 'writeback-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux

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* 'writeback-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux:
  writeback: set max_pause to lowest value on zero bdi_dirty
  writeback: permit through good bdi even when global dirty exceeded
  writeback: comment on the bdi dirty threshold
  fs: Make write(2) interruptible by a fatal signal
  writeback: Fix issue on make htmldocs
This commit is contained in:
Linus Torvalds 2011-12-13 14:58:56 -08:00
commit 4dde6dedad
3 changed files with 37 additions and 6 deletions
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5
fs/fs-writeback.c
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@ -156,6 +156,7 @@ __bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
* bdi_start_writeback - start writeback
* @bdi: the backing device to write from
* @nr_pages: the number of pages to write
* @reason: reason why some writeback work was initiated
*
* Description:
* This does WB_SYNC_NONE opportunistic writeback. The IO is only
@ -1223,6 +1224,7 @@ static void wait_sb_inodes(struct super_block *sb)
* writeback_inodes_sb_nr - writeback dirty inodes from given super_block
* @sb: the superblock
* @nr: the number of pages to write
* @reason: reason why some writeback work initiated
*
* Start writeback on some inodes on this super_block. No guarantees are made
* on how many (if any) will be written, and this function does not wait
@ -1251,6 +1253,7 @@ EXPORT_SYMBOL(writeback_inodes_sb_nr);
/**
* writeback_inodes_sb - writeback dirty inodes from given super_block
* @sb: the superblock
* @reason: reason why some writeback work was initiated
*
* Start writeback on some inodes on this super_block. No guarantees are made
* on how many (if any) will be written, and this function does not wait
@ -1265,6 +1268,7 @@ EXPORT_SYMBOL(writeback_inodes_sb);
/**
* writeback_inodes_sb_if_idle - start writeback if none underway
* @sb: the superblock
* @reason: reason why some writeback work was initiated
*
* Invoke writeback_inodes_sb if no writeback is currently underway.
* Returns 1 if writeback was started, 0 if not.
@ -1285,6 +1289,7 @@ EXPORT_SYMBOL(writeback_inodes_sb_if_idle);
* writeback_inodes_sb_if_idle - start writeback if none underway
* @sb: the superblock
* @nr: the number of pages to write
* @reason: reason why some writeback work was initiated
*
* Invoke writeback_inodes_sb if no writeback is currently underway.
* Returns 1 if writeback was started, 0 if not.

6
mm/filemap.c
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@ -2407,7 +2407,6 @@ static ssize_t generic_perform_write(struct file *file,
iov_iter_count(i));
again:
/*
* Bring in the user page that we will copy from _first_.
* Otherwise there's a nasty deadlock on copying from the
@ -2463,7 +2462,10 @@ static ssize_t generic_perform_write(struct file *file,
written += copied;
balance_dirty_pages_ratelimited(mapping);
if (fatal_signal_pending(current)) {
status = -EINTR;
break;
}
} while (iov_iter_count(i));
return written ? written : status;

32
mm/page-writeback.c
View File

@ -411,8 +411,13 @@ void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty)
*
* Returns @bdi's dirty limit in pages. The term "dirty" in the context of
* dirty balancing includes all PG_dirty, PG_writeback and NFS unstable pages.
* And the "limit" in the name is not seriously taken as hard limit in
* balance_dirty_pages().
*
* Note that balance_dirty_pages() will only seriously take it as a hard limit
* when sleeping max_pause per page is not enough to keep the dirty pages under
* control. For example, when the device is completely stalled due to some error
* conditions, or when there are 1000 dd tasks writing to a slow 10MB/s USB key.
* In the other normal situations, it acts more gently by throttling the tasks
* more (rather than completely block them) when the bdi dirty pages go high.
*
* It allocates high/low dirty limits to fast/slow devices, in order to prevent
* - starving fast devices
@ -594,6 +599,13 @@ static unsigned long bdi_position_ratio(struct backing_dev_info *bdi,
*/
if (unlikely(bdi_thresh > thresh))
bdi_thresh = thresh;
/*
* It's very possible that bdi_thresh is close to 0 not because the
* device is slow, but that it has remained inactive for long time.
* Honour such devices a reasonable good (hopefully IO efficient)
* threshold, so that the occasional writes won't be blocked and active
* writes can rampup the threshold quickly.
*/
bdi_thresh = max(bdi_thresh, (limit - dirty) / 8);
/*
* scale global setpoint to bdi's:
@ -977,8 +989,7 @@ static unsigned long bdi_max_pause(struct backing_dev_info *bdi,
*
* 8 serves as the safety ratio.
*/
if (bdi_dirty)
t = min(t, bdi_dirty * HZ / (8 * bw + 1));
t = min(t, bdi_dirty * HZ / (8 * bw + 1));
/*
* The pause time will be settled within range (max_pause/4, max_pause).
@ -1136,6 +1147,19 @@ static void balance_dirty_pages(struct address_space *mapping,
if (task_ratelimit)
break;
/*
* In the case of an unresponding NFS server and the NFS dirty
* pages exceeds dirty_thresh, give the other good bdi's a pipe
* to go through, so that tasks on them still remain responsive.
*
* In theory 1 page is enough to keep the comsumer-producer
* pipe going: the flusher cleans 1 page => the task dirties 1
* more page. However bdi_dirty has accounting errors. So use
* the larger and more IO friendly bdi_stat_error.
*/
if (bdi_dirty <= bdi_stat_error(bdi))
break;
if (fatal_signal_pending(current))
break;
}