Messages in this thread Patch in this message | | | Date | Fri, 21 Apr 2006 22:29:36 -0400 | From | Shailabh Nagar <> | Subject | [Patch 2/8] Sync block I/O and swapin delay collection |
| |
Changelog
Fixes comments by akpm - avoid creating new per-process flag PF_SWAPIN
delayacct-blkio-swapin.patch
Collect per-task block I/O delay statistics.
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>
include/linux/delayacct.h | 25 +++++++++++++++++++++++++ include/linux/sched.h | 6 ++++++ kernel/delayacct.c | 19 +++++++++++++++++++ kernel/sched.c | 5 +++++ mm/memory.c | 4 ++++ 5 files changed, 59 insertions(+)
Index: linux-2.6.17-rc1/include/linux/delayacct.h =================================================================== --- linux-2.6.17-rc1.orig/include/linux/delayacct.h 2006-04-21 22:27:18.000000000 -0400 +++ linux-2.6.17-rc1/include/linux/delayacct.h 2006-04-21 22:27:19.000000000 -0400 @@ -19,6 +19,13 @@
#include <linux/sched.h>
+/* + * Per-task flags relevant to delay accounting + * maintained privately to avoid exhausting similar flags in sched.h:PF_* + * Used to set current->delays->flags + */ +#define DELAYACCT_PF_SWAPIN 0x00000001 /* I am doing a swapin */ + #ifdef CONFIG_TASK_DELAY_ACCT
extern int delayacct_on; /* Delay accounting turned on/off */ @@ -26,6 +33,8 @@ extern kmem_cache_t *delayacct_cache; extern void delayacct_init(void); extern void __delayacct_tsk_init(struct task_struct *); extern void __delayacct_tsk_exit(struct task_struct *); +extern void __delayacct_blkio_start(void); +extern void __delayacct_blkio_end(void);
static inline void delayacct_set_flag(int flag) { @@ -53,6 +62,18 @@ static inline void delayacct_tsk_exit(st __delayacct_tsk_exit(tsk); }
+static inline void delayacct_blkio_start(void) +{ + if (current->delays) + __delayacct_blkio_start(); +} + +static inline void delayacct_blkio_end(void) +{ + if (current->delays) + __delayacct_blkio_end(); +} + #else static inline void delayacct_set_flag(int flag) {} @@ -64,6 +85,10 @@ static inline void delayacct_tsk_init(st {} static inline void delayacct_tsk_exit(struct task_struct *tsk) {} +static inline void delayacct_blkio_start(void) +{} +static inline void delayacct_blkio_end(void) +{} #endif /* CONFIG_TASK_DELAY_ACCT */
#endif Index: linux-2.6.17-rc1/kernel/delayacct.c =================================================================== --- linux-2.6.17-rc1.orig/kernel/delayacct.c 2006-04-21 22:27:18.000000000 -0400 +++ linux-2.6.17-rc1/kernel/delayacct.c 2006-04-21 22:27:19.000000000 -0400 @@ -85,3 +85,22 @@ static inline void delayacct_end(struct spin_unlock(¤t->delays->lock); }
+void __delayacct_blkio_start(void) +{ + delayacct_start(¤t->delays->blkio_start); +} + +void __delayacct_blkio_end(void) +{ + if (current->delays->flags & DELAYACCT_PF_SWAPIN) + /* Swapin block I/O */ + delayacct_end(¤t->delays->blkio_start, + ¤t->delays->blkio_end, + ¤t->delays->swapin_delay, + ¤t->delays->swapin_count); + else /* Other block I/O */ + delayacct_end(¤t->delays->blkio_start, + ¤t->delays->blkio_end, + ¤t->delays->blkio_delay, + ¤t->delays->blkio_count); +} Index: linux-2.6.17-rc1/include/linux/sched.h =================================================================== --- linux-2.6.17-rc1.orig/include/linux/sched.h 2006-04-21 22:27:18.000000000 -0400 +++ linux-2.6.17-rc1/include/linux/sched.h 2006-04-21 22:27:19.000000000 -0400 @@ -550,6 +550,12 @@ struct task_delay_info { * Atomicity of updates to XXX_delay, XXX_count protected by * single lock above (split into XXX_lock if contention is an issue). */ + + struct timespec blkio_start, blkio_end; /* Shared by blkio, swapin */ + u64 blkio_delay; /* wait for sync block io completion */ + u64 swapin_delay; /* wait for swapin block io completion */ + u32 blkio_count; + u32 swapin_count; }; #endif
Index: linux-2.6.17-rc1/kernel/sched.c =================================================================== --- linux-2.6.17-rc1.orig/kernel/sched.c 2006-04-21 22:27:18.000000000 -0400 +++ linux-2.6.17-rc1/kernel/sched.c 2006-04-21 22:27:19.000000000 -0400 @@ -50,6 +50,7 @@ #include <linux/times.h> #include <linux/acct.h> #include <linux/kprobes.h> +#include <linux/delayacct.h> #include <asm/tlb.h>
#include <asm/unistd.h> @@ -4144,9 +4145,11 @@ void __sched io_schedule(void) { struct runqueue *rq = &per_cpu(runqueues, raw_smp_processor_id());
+ delayacct_blkio_start(); atomic_inc(&rq->nr_iowait); schedule(); atomic_dec(&rq->nr_iowait); + delayacct_blkio_end(); }
EXPORT_SYMBOL(io_schedule); @@ -4156,9 +4159,11 @@ long __sched io_schedule_timeout(long ti struct runqueue *rq = &per_cpu(runqueues, raw_smp_processor_id()); long ret;
+ delayacct_blkio_start(); atomic_inc(&rq->nr_iowait); ret = schedule_timeout(timeout); atomic_dec(&rq->nr_iowait); + delayacct_blkio_end(); return ret; }
Index: linux-2.6.17-rc1/mm/memory.c =================================================================== --- linux-2.6.17-rc1.orig/mm/memory.c 2006-04-21 22:27:18.000000000 -0400 +++ linux-2.6.17-rc1/mm/memory.c 2006-04-21 22:27:19.000000000 -0400 @@ -48,6 +48,7 @@ #include <linux/rmap.h> #include <linux/module.h> #include <linux/init.h> +#include <linux/delayacct.h>
#include <asm/pgalloc.h> #include <asm/uaccess.h> @@ -1880,6 +1881,7 @@ static int do_swap_page(struct mm_struct
entry = pte_to_swp_entry(orig_pte); again: + delayacct_set_flag(DELAYACCT_PF_SWAPIN); page = lookup_swap_cache(entry); if (!page) { swapin_readahead(entry, address, vma); @@ -1892,6 +1894,7 @@ again: page_table = pte_offset_map_lock(mm, pmd, address, &ptl); if (likely(pte_same(*page_table, orig_pte))) ret = VM_FAULT_OOM; + delayacct_clear_flag(DELAYACCT_PF_SWAPIN); goto unlock; }
@@ -1903,6 +1906,7 @@ again:
mark_page_accessed(page); lock_page(page); + delayacct_clear_flag(DELAYACCT_PF_SWAPIN); if (!PageSwapCache(page)) { /* Page migration has occured */ unlock_page(page); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |