Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751785AbVLGWXV (ORCPT ); Wed, 7 Dec 2005 17:23:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751793AbVLGWXV (ORCPT ); Wed, 7 Dec 2005 17:23:21 -0500 Received: from e33.co.us.ibm.com ([32.97.110.151]:26263 "EHLO e33.co.us.ibm.com") by vger.kernel.org with ESMTP id S1751785AbVLGWXU (ORCPT ); Wed, 7 Dec 2005 17:23:20 -0500 Message-ID: <439760CE.7050401@watson.ibm.com> Date: Wed, 07 Dec 2005 22:23:10 +0000 From: Shailabh Nagar User-Agent: Debian Thunderbird 1.0.2 (X11/20051002) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Shailabh Nagar CC: linux-kernel , elsa-devel , lse-tech@lists.sourceforge.net, ckrm-tech , Guillaume Thouvenin , Jay Lan , Jens Axboe , Suparna Bhattacharya Subject: [RFC][Patch 3/5] Per-task delay accounting: Sync block I/O delays References: <43975D45.3080801@watson.ibm.com> In-Reply-To: <43975D45.3080801@watson.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7875 Lines: 258 This patch attempts to record all the time spent by a task waiting for completion of (user-initiated) block I/O. Ideally, it would have been nice to be able to record the time spent by a task waiting for I/O events that are related to async block I/O. While that can be done now (by measuring time spent in wait_for_async_kiocb) once (if ?) network aio is implemented, AFAIK, it won't be possible to distinguish async block and network aio events (and I suspect async I/O to pipes too...) so async block I/O gets ignored for now. Suggestions on how async block I/O wait can be accounted accurately would be welcome. Changes since 11/14/05 - use nanosecond resolution, adjusted wall clock time for timestamps instead of sched_clock (akpm, andi, marcelo) - collect stats only if delay accounting enabled (parag) - stats collected for delays in all userspace-initiated block I/O including fsync/fdatasync but not counting waits for async block io events. 11/14/05: First post delayacct-blkio.patch Record time spent by a task waiting for completion of userspace initiated synchronous block I/O. This can help determine the right I/O priority for the task. Signed-off-by: Shailabh Nagar fs/buffer.c | 6 ++++++ fs/read_write.c | 10 +++++++++- include/linux/delayacct.h | 4 ++++ include/linux/sched.h | 2 ++ kernel/delayacct.c | 31 +++++++++++++++++++++++++++++++ mm/filemap.c | 10 +++++++++- mm/memory.c | 17 +++++++++++++++-- 7 files changed, 76 insertions(+), 4 deletions(-) Index: linux-2.6.15-rc5/include/linux/sched.h =================================================================== --- linux-2.6.15-rc5.orig/include/linux/sched.h +++ linux-2.6.15-rc5/include/linux/sched.h @@ -546,6 +546,8 @@ struct task_delay_info { spinlock_t lock; /* Add stats in pairs: uint64_t delay, uint32_t count */ + uint64_t blkio_delay; /* wait for sync block io completion */ + uint32_t blkio_count; }; #endif Index: linux-2.6.15-rc5/fs/read_write.c =================================================================== --- linux-2.6.15-rc5.orig/fs/read_write.c +++ linux-2.6.15-rc5/fs/read_write.c @@ -14,6 +14,8 @@ #include #include #include +#include +#include #include #include @@ -224,8 +226,14 @@ ssize_t do_sync_read(struct file *filp, (ret = filp->f_op->aio_read(&kiocb, buf, len, kiocb.ki_pos))) wait_on_retry_sync_kiocb(&kiocb); - if (-EIOCBQUEUED == ret) + if (-EIOCBQUEUED == ret) { + __attribute__((unused)) struct timespec start, end; + + getnstimestamp(&start); ret = wait_on_sync_kiocb(&kiocb); + getnstimestamp(&end); + delayacct_blkio(&start, &end); + } *ppos = kiocb.ki_pos; return ret; } Index: linux-2.6.15-rc5/mm/filemap.c =================================================================== --- linux-2.6.15-rc5.orig/mm/filemap.c +++ linux-2.6.15-rc5/mm/filemap.c @@ -28,6 +28,8 @@ #include #include #include +#include +#include #include "filemap.h" /* * FIXME: remove all knowledge of the buffer layer from the core VM @@ -1062,8 +1064,14 @@ generic_file_read(struct file *filp, cha init_sync_kiocb(&kiocb, filp); ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos); - if (-EIOCBQUEUED == ret) + if (-EIOCBQUEUED == ret) { + __attribute__((unused)) struct timespec start, end; + + getnstimestamp(&start); ret = wait_on_sync_kiocb(&kiocb); + getnstimestamp(&end); + delayacct_blkio(&start, &end); + } return ret; } Index: linux-2.6.15-rc5/mm/memory.c =================================================================== --- linux-2.6.15-rc5.orig/mm/memory.c +++ linux-2.6.15-rc5/mm/memory.c @@ -48,6 +48,8 @@ #include #include #include +#include +#include #include #include @@ -2200,11 +2202,22 @@ static inline int handle_pte_fault(struc old_entry = entry = *pte; if (!pte_present(entry)) { if (pte_none(entry)) { + int ret; + __attribute__((unused)) struct timespec start, end; + if (!vma->vm_ops || !vma->vm_ops->nopage) return do_anonymous_page(mm, vma, address, pte, pmd, write_access); - return do_no_page(mm, vma, address, - pte, pmd, write_access); + + if (vma->vm_file) + getnstimestamp(&start); + ret = do_no_page(mm, vma, address, + pte, pmd, write_access); + if (vma->vm_file) { + getnstimestamp(&end); + delayacct_blkio(&start, &end); + } + return ret; } if (pte_file(entry)) return do_file_page(mm, vma, address, Index: linux-2.6.15-rc5/fs/buffer.c =================================================================== --- linux-2.6.15-rc5.orig/fs/buffer.c +++ linux-2.6.15-rc5/fs/buffer.c @@ -41,6 +41,8 @@ #include #include #include +#include +#include static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); static void invalidate_bh_lrus(void); @@ -337,6 +339,7 @@ static long do_fsync(unsigned int fd, in struct file * file; struct address_space *mapping; int ret, err; + __attribute__((unused)) struct timespec start, end; ret = -EBADF; file = fget(fd); @@ -349,6 +352,7 @@ static long do_fsync(unsigned int fd, in goto out_putf; } + getnstimestamp(&start); mapping = file->f_mapping; current->flags |= PF_SYNCWRITE; @@ -371,6 +375,8 @@ static long do_fsync(unsigned int fd, in out_putf: fput(file); out: + getnstimestamp(&end); + delayacct_blkio(&start, &end); return ret; } Index: linux-2.6.15-rc5/include/linux/delayacct.h =================================================================== --- linux-2.6.15-rc5.orig/include/linux/delayacct.h +++ linux-2.6.15-rc5/include/linux/delayacct.h @@ -19,8 +19,12 @@ #ifdef CONFIG_TASK_DELAY_ACCT extern int delayacct_on; /* Delay accounting turned on/off */ extern void delayacct_tsk_init(struct task_struct *tsk); +extern void delayacct_blkio(struct timespec *start, struct timespec *end); #else static inline void delayacct_tsk_init(struct task_struct *tsk) {} +static inline void delayacct_blkio(struct timespec *start, struct timespec *end) +{} + #endif /* CONFIG_TASK_DELAY_ACCT */ #endif /* _LINUX_TASKDELAYS_H */ Index: linux-2.6.15-rc5/kernel/delayacct.c =================================================================== --- linux-2.6.15-rc5.orig/kernel/delayacct.c +++ linux-2.6.15-rc5/kernel/delayacct.c @@ -12,6 +12,7 @@ */ #include +#include int delayacct_on; /* Delay accounting turned on/off */ @@ -34,3 +35,33 @@ static int __init delayacct_init(void) return 0; } core_initcall(delayacct_init); + +inline void delayacct_blkio(struct timespec *start, struct timespec *end) +{ + unsigned long long delay; + + if (!delayacct_on) + return; + + delay = timespec_nsdiff(start, end); + + spin_lock(¤t->delays.lock); + current->delays.blkio_delay += delay; + current->delays.blkio_count++; + spin_unlock(¤t->delays.lock); +} + +inline void delayacct_swapin(struct timespec *start, struct timespec *end) +{ + unsigned long long delay; + + if (!delayacct_on) + return; + + delay = timespec_nsdiff(start, end); + + spin_lock(¤t->delays.lock); + current->delays.swapin_delay += delay; + current->delays.swapin_count++; + spin_unlock(¤t->delays.lock); +} - 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/