Messages in this thread Patch in this message | | | Date | Wed, 29 Mar 2006 19:37:10 -0500 | From | Shailabh Nagar <> | Subject | [Patch 2/8] Block I/O, swapin delays |
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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 | 16 ++++++++++++++++ include/linux/sched.h | 7 +++++++ kernel/delayacct.c | 18 ++++++++++++++++++ kernel/sched.c | 5 +++++ mm/memory.c | 4 ++++ 5 files changed, 50 insertions(+)
Index: linux-2.6.16/include/linux/delayacct.h =================================================================== --- linux-2.6.16.orig/include/linux/delayacct.h 2006-03-29 18:12:57.000000000 -0500 +++ linux-2.6.16/include/linux/delayacct.h 2006-03-29 18:13:13.000000000 -0500 @@ -25,6 +25,8 @@ 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_tsk_init(struct task_struct *tsk) { @@ -40,6 +42,16 @@ 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_init(void) {} @@ -47,5 +59,9 @@ 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 /* _LINUX_TASKDELAYS_H */ Index: linux-2.6.16/kernel/delayacct.c =================================================================== --- linux-2.6.16.orig/kernel/delayacct.c 2006-03-29 18:12:57.000000000 -0500 +++ linux-2.6.16/kernel/delayacct.c 2006-03-29 18:13:13.000000000 -0500 @@ -90,3 +90,21 @@ 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->flags & PF_SWAPIN) /* Swapping a page in */ + 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-2.6.16/include/linux/sched.h =================================================================== --- linux-2.6.16.orig/include/linux/sched.h 2006-03-29 18:12:57.000000000 -0500 +++ linux-2.6.16/include/linux/sched.h 2006-03-29 18:13:13.000000000 -0500 @@ -550,6 +550,12 @@ struct task_delay_info { * u64 XXX_delay; * u32 XXX_count; */ + + struct timespec blkio_start, blkio_end; /* Shared by blkio, swapin */ + u64 blkio_delay; /* wait for sync block io completion */ + u64 swapin_delay; /* wait for sync block io completion */ + u32 blkio_count; + u32 swapin_count; }; #endif
@@ -945,6 +951,7 @@ static inline void put_task_struct(struc #define PF_BORROWED_MM 0x00400000 /* I am a kthread doing use_mm */ #define PF_RANDOMIZE 0x00800000 /* randomize virtual address space */ #define PF_SWAPWRITE 0x01000000 /* Allowed to write to swap */ +#define PF_SWAPIN 0x02000000 /* I am doing a swap in */
/* * Only the _current_ task can read/write to tsk->flags, but other Index: linux-2.6.16/kernel/sched.c =================================================================== --- linux-2.6.16.orig/kernel/sched.c 2006-03-29 18:12:54.000000000 -0500 +++ linux-2.6.16/kernel/sched.c 2006-03-29 18:13:13.000000000 -0500 @@ -49,6 +49,7 @@ #include <linux/syscalls.h> #include <linux/times.h> #include <linux/acct.h> +#include <linux/delayacct.h> #include <asm/tlb.h>
#include <asm/unistd.h> @@ -4112,9 +4113,11 @@ 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); @@ -4124,9 +4127,11 @@ 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-2.6.16/mm/memory.c =================================================================== --- linux-2.6.16.orig/mm/memory.c 2006-03-29 18:12:54.000000000 -0500 +++ linux-2.6.16/mm/memory.c 2006-03-29 18:13:13.000000000 -0500 @@ -1883,6 +1883,7 @@ static int do_swap_page(struct mm_struct
entry = pte_to_swp_entry(orig_pte); again: + current->flags |= PF_SWAPIN; page = lookup_swap_cache(entry); if (!page) { swapin_readahead(entry, address, vma); @@ -1895,6 +1896,7 @@ again: page_table = pte_offset_map_lock(mm, pmd, address, &ptl); if (likely(pte_same(*page_table, orig_pte))) ret = VM_FAULT_OOM; + current->flags &= ~PF_SWAPIN; goto unlock; }
@@ -1906,6 +1908,8 @@ again:
mark_page_accessed(page); lock_page(page); + current->flags &= ~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/
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