d234154125
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>
85 lines
2.1 KiB
C
85 lines
2.1 KiB
C
/*
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* Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
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* All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef __XFS_SUPPORT_KTRACE_H__
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#define __XFS_SUPPORT_KTRACE_H__
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/*
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* Trace buffer entry structure.
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*/
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typedef struct ktrace_entry {
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void *val[16];
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} ktrace_entry_t;
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/*
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* Trace buffer header structure.
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*/
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typedef struct ktrace {
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int kt_nentries; /* number of entries in trace buf */
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atomic_t kt_index; /* current index in entries */
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unsigned int kt_index_mask;
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int kt_rollover;
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ktrace_entry_t *kt_entries; /* buffer of entries */
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} ktrace_t;
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/*
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* Trace buffer snapshot structure.
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*/
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typedef struct ktrace_snap {
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int ks_start; /* kt_index at time of snap */
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int ks_index; /* current index */
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} ktrace_snap_t;
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#ifdef CONFIG_XFS_TRACE
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extern void ktrace_init(int zentries);
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extern void ktrace_uninit(void);
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extern ktrace_t *ktrace_alloc(int, unsigned int __nocast);
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extern void ktrace_free(ktrace_t *);
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extern void ktrace_enter(
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ktrace_t *,
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void *,
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void *,
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void *,
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void *,
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void *,
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void *,
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void *,
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void *,
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void *,
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void *,
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void *,
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void *,
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void *,
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void *,
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void *,
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void *);
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extern ktrace_entry_t *ktrace_first(ktrace_t *, ktrace_snap_t *);
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extern int ktrace_nentries(ktrace_t *);
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extern ktrace_entry_t *ktrace_next(ktrace_t *, ktrace_snap_t *);
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extern ktrace_entry_t *ktrace_skip(ktrace_t *, int, ktrace_snap_t *);
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#else
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#define ktrace_init(x) do { } while (0)
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#define ktrace_uninit() do { } while (0)
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#endif /* CONFIG_XFS_TRACE */
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#endif /* __XFS_SUPPORT_KTRACE_H__ */
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