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authorThomas Gleixner <tglx@linutronix.de>2009-06-16 15:33:39 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-16 19:47:48 -0700
commit8b0b1db0133e4218a9b45c09e53793c039edebe1 (patch)
tree551ec8a69652b9856cefcf537bdcfd262f356974 /fs
parent10fc89d01a7ea2ecc2a58d2f4e7700f47178cd62 (diff)
downloadlinux-8b0b1db0133e4218a9b45c09e53793c039edebe1.tar.gz
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.h6
1 files changed, 3 insertions, 3 deletions
diff --git a/fs/nfs/iostat.h b/fs/nfs/iostat.h
index a2ab2529b5c..ceda50aad73 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