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| author | David Chinner <dgc@sgi.com> | 2008-03-06 05:45:43 +0300 |
|---|---|---|
| committer | Lachlan McIlroy <lachlan@redback.melbourne.sgi.com> | 2008-04-18 05:40:04 +0400 |
| commit | d234154125197053d5215711b5df867979e55ebd (patch) | |
| tree | 366a6ff91b514a8f9846ac82926e0bbfd0a1fbed /fs/xfs/support/ktrace.h | |
| parent | 6ee4752ffe782be6e86bea1403a2fe0f682aa71a (diff) | |
| download | linux-d234154125197053d5215711b5df867979e55ebd.tar.xz | |
[XFS] Use power-of-2 sized buffers to reduce overhead
Now that the ktrace_enter() code is using atomics, the non-power-of-2
buffer sizes - which require modulus operations to get the index - are
showing up as using substantial CPU in the profiles.
Force the buffer sizes to be rounded up to the nearest power of two and
use masking rather than modulus operations to convert the index counter to
the buffer index. This reduces ktrace_enter overhead to 8% of a CPU time,
and again almost halves the trace intensive test runtime.
SGI-PV: 977546
SGI-Modid: xfs-linux-melb:xfs-kern:30538a
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Diffstat (limited to 'fs/xfs/support/ktrace.h')
| -rw-r--r-- | fs/xfs/support/ktrace.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/xfs/support/ktrace.h b/fs/xfs/support/ktrace.h index 782dbbb6a9d0..741d6947ca60 100644 --- a/fs/xfs/support/ktrace.h +++ b/fs/xfs/support/ktrace.h @@ -31,6 +31,7 @@ typedef struct ktrace_entry { typedef struct ktrace { int kt_nentries; /* number of entries in trace buf */ atomic_t kt_index; /* current index in entries */ + unsigned int kt_index_mask; int kt_rollover; ktrace_entry_t *kt_entries; /* buffer of entries */ } ktrace_t; |