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| author |   Thomas Gleixner <tglx@linutronix.de> | 2009-06-16 15:33:39 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2009-06-16 19:47:48 -0700 |
| commit | 8b0b1db0133e4218a9b45c09e53793c039edebe1 (patch) | |
| tree | 551ec8a69652b9856cefcf537bdcfd262f356974 /fs | |
| parent | drbd: add major number to major.h (diff) | |
| download | linux-dev-8b0b1db0133e4218a9b45c09e53793c039edebe1.tar.xz linux-dev-8b0b1db0133e4218a9b45c09e53793c039edebe1.zip | |
remove put_cpu_no_resched()
put_cpu_no_resched() is an optimization of put_cpu() which unfortunately
can cause high latencies.
The nfs iostats code uses put_cpu_no_resched() in a code sequence where a
reschedule request caused by an interrupt between the get_cpu() and the
put_cpu_no_resched() can delay the reschedule for at least HZ.
The other users of put_cpu_no_resched() optimize correctly in interrupt
code, but there is no real harm in using the put_cpu() function which is
an alias for preempt_enable(). The extra check of the preemmpt count is
not as critical as the potential source of missing a reschedule.
Debugged in the preempt-rt tree and verified in mainline.
Impact: remove a high latency source
[akpm@linux-foundation.org: build fix]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/nfs/iostat.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/fs/nfs/iostat.h b/fs/nfs/iostat.h index a2ab2529b5ca..ceda50aad73c 100644 --- a/fs/nfs/iostat.h +++ b/fs/nfs/iostat.h @@ -31,7 +31,7 @@ static inline void nfs_inc_server_stats(const struct nfs_server *server, cpu = get_cpu(); iostats = per_cpu_ptr(server->io_stats, cpu); iostats->events[stat]++; - put_cpu_no_resched(); + put_cpu(); } static inline void nfs_inc_stats(const struct inode *inode, @@ -50,7 +50,7 @@ static inline void nfs_add_server_stats(const struct nfs_server *server, cpu = get_cpu(); iostats = per_cpu_ptr(server->io_stats, cpu); iostats->bytes[stat] += addend; - put_cpu_no_resched(); + put_cpu(); } static inline void nfs_add_stats(const struct inode *inode, @@ -71,7 +71,7 @@ static inline void nfs_add_fscache_stats(struct inode *inode, cpu = get_cpu(); iostats = per_cpu_ptr(NFS_SERVER(inode)->io_stats, cpu); iostats->fscache[stat] += addend; - put_cpu_no_resched(); + put_cpu(); } #endif |