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| author | Eric Dumazet <dada1@cosmosbay.com> | 2009-01-06 14:41:04 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-01-06 15:59:13 -0800 |
| commit | 179f7ebff6be45738c6e2fa68c8d2cc5c2c6308e (patch) | |
| tree | 3d48b5f825cfa29f5b39656503c5157872454e9f /fs/ext4/ext4.h | |
| parent | e3d5a27d5862b6425d0879272e24abecf7245105 (diff) | |
| download | lwn-179f7ebff6be45738c6e2fa68c8d2cc5c2c6308e.tar.gz lwn-179f7ebff6be45738c6e2fa68c8d2cc5c2c6308e.zip | |
percpu_counter: FBC_BATCH should be a variable
For NR_CPUS >= 16 values, FBC_BATCH is 2*NR_CPUS
Considering more and more distros are using high NR_CPUS values, it makes
sense to use a more sensible value for FBC_BATCH, and get rid of NR_CPUS.
A sensible value is 2*num_online_cpus(), with a minimum value of 32 (This
minimum value helps branch prediction in __percpu_counter_add())
We already have a hotcpu notifier, so we can adjust FBC_BATCH dynamically.
We rename FBC_BATCH to percpu_counter_batch since its not a constant
anymore.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/ext4/ext4.h')
| -rw-r--r-- | fs/ext4/ext4.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index b0537c827024..6c46c648430d 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1225,11 +1225,11 @@ do { \ } while (0) #ifdef CONFIG_SMP -/* Each CPU can accumulate FBC_BATCH blocks in their local +/* Each CPU can accumulate percpu_counter_batch blocks in their local * counters. So we need to make sure we have free blocks more - * than FBC_BATCH * nr_cpu_ids. Also add a window of 4 times. + * than percpu_counter_batch * nr_cpu_ids. Also add a window of 4 times. */ -#define EXT4_FREEBLOCKS_WATERMARK (4 * (FBC_BATCH * nr_cpu_ids)) +#define EXT4_FREEBLOCKS_WATERMARK (4 * (percpu_counter_batch * nr_cpu_ids)) #else #define EXT4_FREEBLOCKS_WATERMARK 0 #endif |