![Shailabh Nagar](/assets/img/avatar_default.png)
Unlike earlier iterations of the delay accounting patches, now delays are only collected for the actual I/O waits rather than try and cover the delays seen in I/O submission paths. Account separately for block I/O delays incurred as a result of swapin page faults whose frequency can be affected by the task/process' rss limit. Hence swapin delays can act as feedback for rss limit changes independent of I/O priority changes. Signed-off-by: Shailabh Nagar <nagar@watson.ibm.com> Signed-off-by: Balbir Singh <balbir@in.ibm.com> Cc: Jes Sorensen <jes@sgi.com> Cc: Peter Chubb <peterc@gelato.unsw.edu.au> Cc: Erich Focht <efocht@ess.nec.de> Cc: Levent Serinol <lserinol@gmail.com> Cc: Jay Lan <jlan@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
107 lines
2.6 KiB
C
107 lines
2.6 KiB
C
/* delayacct.c - per-task delay accounting
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*
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* Copyright (C) Shailabh Nagar, IBM Corp. 2006
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it would be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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* the GNU General Public License for more details.
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*/
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/time.h>
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#include <linux/sysctl.h>
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#include <linux/delayacct.h>
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int delayacct_on __read_mostly; /* Delay accounting turned on/off */
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kmem_cache_t *delayacct_cache;
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static int __init delayacct_setup_enable(char *str)
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{
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delayacct_on = 1;
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return 1;
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}
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__setup("delayacct", delayacct_setup_enable);
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void delayacct_init(void)
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{
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delayacct_cache = kmem_cache_create("delayacct_cache",
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sizeof(struct task_delay_info),
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0,
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SLAB_PANIC,
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NULL, NULL);
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delayacct_tsk_init(&init_task);
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}
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void __delayacct_tsk_init(struct task_struct *tsk)
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{
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tsk->delays = kmem_cache_zalloc(delayacct_cache, SLAB_KERNEL);
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if (tsk->delays)
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spin_lock_init(&tsk->delays->lock);
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}
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void __delayacct_tsk_exit(struct task_struct *tsk)
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{
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kmem_cache_free(delayacct_cache, tsk->delays);
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tsk->delays = NULL;
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}
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/*
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* Start accounting for a delay statistic using
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* its starting timestamp (@start)
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*/
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static inline void delayacct_start(struct timespec *start)
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{
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do_posix_clock_monotonic_gettime(start);
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}
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/*
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* Finish delay accounting for a statistic using
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* its timestamps (@start, @end), accumalator (@total) and @count
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*/
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static void delayacct_end(struct timespec *start, struct timespec *end,
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u64 *total, u32 *count)
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{
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struct timespec ts;
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s64 ns;
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do_posix_clock_monotonic_gettime(end);
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ts = timespec_sub(*end, *start);
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ns = timespec_to_ns(&ts);
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if (ns < 0)
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return;
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spin_lock(¤t->delays->lock);
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*total += ns;
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(*count)++;
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spin_unlock(¤t->delays->lock);
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}
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void __delayacct_blkio_start(void)
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{
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delayacct_start(¤t->delays->blkio_start);
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}
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void __delayacct_blkio_end(void)
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{
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if (current->delays->flags & DELAYACCT_PF_SWAPIN)
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/* Swapin block I/O */
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delayacct_end(¤t->delays->blkio_start,
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¤t->delays->blkio_end,
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¤t->delays->swapin_delay,
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¤t->delays->swapin_count);
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else /* Other block I/O */
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delayacct_end(¤t->delays->blkio_start,
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¤t->delays->blkio_end,
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¤t->delays->blkio_delay,
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¤t->delays->blkio_count);
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}
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