From: Kent Overstreet <koverstreet@google.com> To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org Cc: akpm@linux-foundation.org, Kent Overstreet <koverstreet@google.com>, Zach Brown <zab@redhat.com>, Felipe Balbi <balbi@ti.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Mark Fasheh <mfasheh@suse.com>, Joel Becker <jlbec@evilplan.org>, Rusty Russell <rusty@rustcorp.com.au>, Jens Axboe <axboe@kernel.dk>, Asai Thambi S P <asamymuthupa@micron.com>, Selvan Mani <smani@micron.com>, Sam Bradshaw <sbradshaw@micron.com>, Jeff Moyer <jmoyer@redhat.com>, Al Viro <viro@zeniv.linux.org.uk>, Benjamin LaHaise <bcrl@kvack.org> Subject: [PATCH 07/21] aio: Don't use ctx->tail unnecessarily Date: Mon, 13 May 2013 18:18:44 -0700 [thread overview] Message-ID: <1368494338-7069-8-git-send-email-koverstreet@google.com> (raw) In-Reply-To: <1368494338-7069-1-git-send-email-koverstreet@google.com> aio_complete() (arguably) needs to keep its own trusted copy of the tail pointer, but io_getevents() doesn't have to use it - it's already using the head pointer from the ring buffer. So convert it to use the tail from the ring buffer so it touches fewer cachelines and doesn't contend with the cacheline aio_complete() needs. Signed-off-by: Kent Overstreet <koverstreet@google.com> Cc: Zach Brown <zab@redhat.com> Cc: Felipe Balbi <balbi@ti.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Jens Axboe <axboe@kernel.dk> Cc: Asai Thambi S P <asamymuthupa@micron.com> Cc: Selvan Mani <smani@micron.com> Cc: Sam Bradshaw <sbradshaw@micron.com> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Benjamin LaHaise <bcrl@kvack.org> --- fs/aio.c | 41 +++++++++++++++++++++++------------------ 1 file changed, 23 insertions(+), 18 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 5e1b801..2c9a5ac 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -306,7 +306,8 @@ static void free_ioctx(struct kioctx *ctx) { struct aio_ring *ring; struct kiocb *req; - unsigned cpu, head, avail; + unsigned cpu, avail; + DEFINE_WAIT(wait); spin_lock_irq(&ctx->ctx_lock); @@ -327,21 +328,24 @@ static void free_ioctx(struct kioctx *ctx) kcpu->reqs_available = 0; } - ring = kmap_atomic(ctx->ring_pages[0]); - head = ring->head; - kunmap_atomic(ring); + while (1) { + prepare_to_wait(&ctx->wait, &wait, TASK_UNINTERRUPTIBLE); - while (atomic_read(&ctx->reqs_available) < ctx->nr_events - 1) { - wait_event(ctx->wait, - (head != ctx->tail) || - (atomic_read(&ctx->reqs_available) >= ctx->nr_events - 1)); - - avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head; + ring = kmap_atomic(ctx->ring_pages[0]); + avail = (ring->head <= ring->tail) + ? ring->tail - ring->head + : ctx->nr_events - ring->head + ring->tail; atomic_add(avail, &ctx->reqs_available); - head += avail; - head %= ctx->nr_events; + ring->head = ring->tail; + kunmap_atomic(ring); + + if (atomic_read(&ctx->reqs_available) >= ctx->nr_events - 1) + break; + + schedule(); } + finish_wait(&ctx->wait, &wait); WARN_ON(atomic_read(&ctx->reqs_available) > ctx->nr_events - 1); @@ -782,7 +786,7 @@ static long aio_read_events_ring(struct kioctx *ctx, struct io_event __user *event, long nr) { struct aio_ring *ring; - unsigned head, pos; + unsigned head, tail, pos; long ret = 0; int copy_ret; @@ -790,11 +794,12 @@ static long aio_read_events_ring(struct kioctx *ctx, ring = kmap_atomic(ctx->ring_pages[0]); head = ring->head; + tail = ring->tail; kunmap_atomic(ring); - pr_debug("h%u t%u m%u\n", head, ctx->tail, ctx->nr_events); + pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events); - if (head == ctx->tail) + if (head == tail) goto out; while (ret < nr) { @@ -802,8 +807,8 @@ static long aio_read_events_ring(struct kioctx *ctx, struct io_event *ev; struct page *page; - avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head; - if (head == ctx->tail) + avail = (head <= tail ? tail : ctx->nr_events) - head; + if (head == tail) break; avail = min(avail, nr - ret); @@ -834,7 +839,7 @@ static long aio_read_events_ring(struct kioctx *ctx, kunmap_atomic(ring); flush_dcache_page(ctx->ring_pages[0]); - pr_debug("%li h%u t%u\n", ret, head, ctx->tail); + pr_debug("%li h%u t%u\n", ret, head, tail); put_reqs_available(ctx, ret); out: -- 1.8.2.1
WARNING: multiple messages have this Message-ID (diff)
From: Kent Overstreet <koverstreet@google.com> To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org Cc: akpm@linux-foundation.org, Kent Overstreet <koverstreet@google.com>, Zach Brown <zab@redhat.com>, Felipe Balbi <balbi@ti.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Mark Fasheh <mfasheh@suse.com>, Joel Becker <jlbec@evilplan.org>, Rusty Russell <rusty@rustcorp.com.au>, Jens Axboe <axboe@kernel.dk>, Asai Thambi S P <asamymuthupa@micron.com>, Selvan Mani <smani@micron.com>, Sam Bradshaw <sbradshaw@micron.com>, Jeff Moyer <jmoyer@redhat.com>, Al Viro <viro@zeniv.linux.org.uk>, Benjamin LaHaise <bcrl@kvack.org> Subject: [PATCH 07/21] aio: Don't use ctx->tail unnecessarily Date: Mon, 13 May 2013 18:18:44 -0700 [thread overview] Message-ID: <1368494338-7069-8-git-send-email-koverstreet@google.com> (raw) In-Reply-To: <1368494338-7069-1-git-send-email-koverstreet@google.com> aio_complete() (arguably) needs to keep its own trusted copy of the tail pointer, but io_getevents() doesn't have to use it - it's already using the head pointer from the ring buffer. So convert it to use the tail from the ring buffer so it touches fewer cachelines and doesn't contend with the cacheline aio_complete() needs. Signed-off-by: Kent Overstreet <koverstreet@google.com> Cc: Zach Brown <zab@redhat.com> Cc: Felipe Balbi <balbi@ti.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Jens Axboe <axboe@kernel.dk> Cc: Asai Thambi S P <asamymuthupa@micron.com> Cc: Selvan Mani <smani@micron.com> Cc: Sam Bradshaw <sbradshaw@micron.com> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Benjamin LaHaise <bcrl@kvack.org> --- fs/aio.c | 41 +++++++++++++++++++++++------------------ 1 file changed, 23 insertions(+), 18 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 5e1b801..2c9a5ac 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -306,7 +306,8 @@ static void free_ioctx(struct kioctx *ctx) { struct aio_ring *ring; struct kiocb *req; - unsigned cpu, head, avail; + unsigned cpu, avail; + DEFINE_WAIT(wait); spin_lock_irq(&ctx->ctx_lock); @@ -327,21 +328,24 @@ static void free_ioctx(struct kioctx *ctx) kcpu->reqs_available = 0; } - ring = kmap_atomic(ctx->ring_pages[0]); - head = ring->head; - kunmap_atomic(ring); + while (1) { + prepare_to_wait(&ctx->wait, &wait, TASK_UNINTERRUPTIBLE); - while (atomic_read(&ctx->reqs_available) < ctx->nr_events - 1) { - wait_event(ctx->wait, - (head != ctx->tail) || - (atomic_read(&ctx->reqs_available) >= ctx->nr_events - 1)); - - avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head; + ring = kmap_atomic(ctx->ring_pages[0]); + avail = (ring->head <= ring->tail) + ? ring->tail - ring->head + : ctx->nr_events - ring->head + ring->tail; atomic_add(avail, &ctx->reqs_available); - head += avail; - head %= ctx->nr_events; + ring->head = ring->tail; + kunmap_atomic(ring); + + if (atomic_read(&ctx->reqs_available) >= ctx->nr_events - 1) + break; + + schedule(); } + finish_wait(&ctx->wait, &wait); WARN_ON(atomic_read(&ctx->reqs_available) > ctx->nr_events - 1); @@ -782,7 +786,7 @@ static long aio_read_events_ring(struct kioctx *ctx, struct io_event __user *event, long nr) { struct aio_ring *ring; - unsigned head, pos; + unsigned head, tail, pos; long ret = 0; int copy_ret; @@ -790,11 +794,12 @@ static long aio_read_events_ring(struct kioctx *ctx, ring = kmap_atomic(ctx->ring_pages[0]); head = ring->head; + tail = ring->tail; kunmap_atomic(ring); - pr_debug("h%u t%u m%u\n", head, ctx->tail, ctx->nr_events); + pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events); - if (head == ctx->tail) + if (head == tail) goto out; while (ret < nr) { @@ -802,8 +807,8 @@ static long aio_read_events_ring(struct kioctx *ctx, struct io_event *ev; struct page *page; - avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head; - if (head == ctx->tail) + avail = (head <= tail ? tail : ctx->nr_events) - head; + if (head == tail) break; avail = min(avail, nr - ret); @@ -834,7 +839,7 @@ static long aio_read_events_ring(struct kioctx *ctx, kunmap_atomic(ring); flush_dcache_page(ctx->ring_pages[0]); - pr_debug("%li h%u t%u\n", ret, head, ctx->tail); + pr_debug("%li h%u t%u\n", ret, head, tail); put_reqs_available(ctx, ret); out: -- 1.8.2.1 -- To unsubscribe, send a message with 'unsubscribe linux-aio' in the body to majordomo@kvack.org. For more info on Linux AIO, see: http://www.kvack.org/aio/ Don't email: <a href=mailto:"aart@kvack.org">aart@kvack.org</a>
next prev parent reply other threads:[~2013-05-14 1:19 UTC|newest] Thread overview: 104+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-05-14 1:18 AIO refactoring/performance improvements/cancellation Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 1:18 ` [PATCH 01/21] aio: fix kioctx not being freed after cancellation at exit time Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 1:18 ` [PATCH 02/21] aio: reqs_active -> reqs_available Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 1:18 ` [PATCH 03/21] aio: percpu reqs_available Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 1:18 ` [PATCH 04/21] Generic percpu refcounting Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 13:51 ` Oleg Nesterov 2013-05-14 13:51 ` Oleg Nesterov 2013-05-15 8:21 ` Kent Overstreet 2013-05-15 8:21 ` Kent Overstreet 2013-05-14 14:59 ` Tejun Heo 2013-05-14 14:59 ` Tejun Heo 2013-05-14 15:28 ` Oleg Nesterov 2013-05-14 15:28 ` Oleg Nesterov 2013-05-15 9:00 ` Kent Overstreet 2013-05-15 9:00 ` Kent Overstreet 2013-05-15 8:58 ` Kent Overstreet 2013-05-15 8:58 ` Kent Overstreet 2013-05-15 17:37 ` Tejun Heo 2013-05-15 17:37 ` Tejun Heo 2013-05-28 23:47 ` Kent Overstreet 2013-05-28 23:47 ` Kent Overstreet 2013-05-29 1:11 ` Tejun Heo 2013-05-29 1:11 ` Tejun Heo 2013-05-29 4:59 ` Rusty Russell 2013-05-29 4:59 ` Rusty Russell 2013-05-31 20:12 ` Kent Overstreet 2013-05-31 20:12 ` Kent Overstreet 2013-05-14 21:59 ` Tejun Heo 2013-05-14 21:59 ` Tejun Heo 2013-05-14 22:15 ` Tejun Heo 2013-05-14 22:15 ` Tejun Heo 2013-05-15 9:07 ` Kent Overstreet 2013-05-15 9:07 ` Kent Overstreet 2013-05-15 17:56 ` Tejun Heo 2013-05-15 17:56 ` Tejun Heo 2013-05-16 0:26 ` Rusty Russell 2013-05-16 0:26 ` Rusty Russell 2013-05-14 1:18 ` [PATCH 05/21] aio: percpu ioctx refcount Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 1:18 ` [PATCH 06/21] aio: io_cancel() no longer returns the io_event Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet [this message] 2013-05-14 1:18 ` [PATCH 07/21] aio: Don't use ctx->tail unnecessarily Kent Overstreet 2013-05-14 1:18 ` [PATCH 08/21] aio: Kill aio_rw_vect_retry() Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 1:18 ` [PATCH 09/21] aio: Kill unneeded kiocb members Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 1:18 ` [PATCH 10/21] aio: Kill ki_users Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 1:18 ` [PATCH 11/21] aio: Kill ki_dtor Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 1:18 ` [PATCH 12/21] aio: convert the ioctx list to radix tree Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 1:18 ` [PATCH 13/21] block: prep work for batch completion Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 1:18 ` [PATCH 14/21] block, aio: batch completion for bios/kiocbs Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 1:18 ` [PATCH 15/21] virtio-blk: convert to batch completion Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 1:18 ` [PATCH 16/21] mtip32xx: " Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 1:18 ` [PATCH 17/21] Percpu tag allocator Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 13:48 ` Oleg Nesterov 2013-05-14 13:48 ` Oleg Nesterov 2013-05-14 14:24 ` Oleg Nesterov 2013-05-14 14:24 ` Oleg Nesterov 2013-05-15 9:34 ` Kent Overstreet 2013-05-15 9:34 ` Kent Overstreet 2013-05-15 9:25 ` Kent Overstreet 2013-05-15 9:25 ` Kent Overstreet 2013-05-15 15:41 ` Oleg Nesterov 2013-05-15 15:41 ` Oleg Nesterov 2013-05-15 16:10 ` Oleg Nesterov 2013-05-15 16:10 ` Oleg Nesterov 2013-06-10 23:20 ` Kent Overstreet 2013-06-10 23:20 ` Kent Overstreet 2013-06-11 17:42 ` Oleg Nesterov 2013-06-11 17:42 ` Oleg Nesterov 2013-05-14 15:03 ` Tejun Heo 2013-05-14 15:03 ` Tejun Heo 2013-05-15 20:19 ` Andi Kleen 2013-05-15 20:19 ` Andi Kleen 2013-05-14 1:18 ` [PATCH 18/21] aio: Allow cancellation without a cancel callback, new kiocb lookup Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 1:18 ` [PATCH 19/21] aio/usb: Update cancellation for new synchonization Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 1:18 ` [PATCH 20/21] direct-io: Set dio->io_error directly Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-14 1:18 ` [PATCH 21/21] block: Bio cancellation Kent Overstreet 2013-05-14 1:18 ` Kent Overstreet 2013-05-15 17:52 ` Jens Axboe 2013-05-15 17:52 ` Jens Axboe 2013-05-15 19:29 ` Kent Overstreet 2013-05-15 19:29 ` Kent Overstreet 2013-05-15 20:01 ` Jens Axboe 2013-05-15 20:01 ` Jens Axboe 2013-05-31 22:52 ` Kent Overstreet 2013-05-31 22:52 ` Kent Overstreet
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