From: Jeff Moyer <jmoyer@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-aio@kvack.org, hch@lst.de
Subject: Re: [PATCH 09/26] aio: only use blk plugs for > 2 depth submissions
Date: Thu, 06 Dec 2018 14:29:44 -0500 [thread overview]
Message-ID: <x49tvjqfo7r.fsf@segfault.boston.devel.redhat.com> (raw)
In-Reply-To: <20181204233729.26776-10-axboe@kernel.dk> (Jens Axboe's message of "Tue, 4 Dec 2018 16:37:12 -0700")
Jens Axboe <axboe@kernel.dk> writes:
> Plugging is meant to optimize submission of a string of IOs, if we don't
> have more than 2 being submitted, don't bother setting up a plug.
Is there really that much overhead in blk_{start|finish}_plug?
-Jeff
>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> ---
> fs/aio.c | 18 ++++++++++++++----
> 1 file changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/fs/aio.c b/fs/aio.c
> index 522c04864d82..ed6c3914477a 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -69,6 +69,12 @@ struct aio_ring {
> struct io_event io_events[0];
> }; /* 128 bytes + ring size */
>
> +/*
> + * Plugging is meant to work with larger batches of IOs. If we don't
> + * have more than the below, then don't bother setting up a plug.
> + */
> +#define AIO_PLUG_THRESHOLD 2
> +
> #define AIO_RING_PAGES 8
>
> struct kioctx_table {
> @@ -1919,7 +1925,8 @@ SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
> if (nr > ctx->nr_events)
> nr = ctx->nr_events;
>
> - blk_start_plug(&plug);
> + if (nr > AIO_PLUG_THRESHOLD)
> + blk_start_plug(&plug);
> for (i = 0; i < nr; i++) {
> struct iocb __user *user_iocb;
>
> @@ -1932,7 +1939,8 @@ SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
> if (ret)
> break;
> }
> - blk_finish_plug(&plug);
> + if (nr > AIO_PLUG_THRESHOLD)
> + blk_finish_plug(&plug);
>
> percpu_ref_put(&ctx->users);
> return i ? i : ret;
> @@ -1959,7 +1967,8 @@ COMPAT_SYSCALL_DEFINE3(io_submit, compat_aio_context_t, ctx_id,
> if (nr > ctx->nr_events)
> nr = ctx->nr_events;
>
> - blk_start_plug(&plug);
> + if (nr > AIO_PLUG_THRESHOLD)
> + blk_start_plug(&plug);
> for (i = 0; i < nr; i++) {
> compat_uptr_t user_iocb;
>
> @@ -1972,7 +1981,8 @@ COMPAT_SYSCALL_DEFINE3(io_submit, compat_aio_context_t, ctx_id,
> if (ret)
> break;
> }
> - blk_finish_plug(&plug);
> + if (nr > AIO_PLUG_THRESHOLD)
> + blk_finish_plug(&plug);
>
> percpu_ref_put(&ctx->users);
> return i ? i : ret;
next prev parent reply other threads:[~2018-12-06 19:29 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-04 23:37 [PATCHSET v5] Support for polled aio Jens Axboe
2018-12-04 23:37 ` [PATCH 01/26] fs: add an iopoll method to struct file_operations Jens Axboe
2018-12-06 19:16 ` Jeff Moyer
2018-12-04 23:37 ` [PATCH 02/26] block: add REQ_HIPRI_ASYNC Jens Axboe
2018-12-04 23:37 ` [PATCH 03/26] block: wire up block device iopoll method Jens Axboe
2018-12-06 19:11 ` Jeff Moyer
2018-12-06 19:14 ` Jens Axboe
2018-12-06 19:15 ` Christoph Hellwig
2018-12-06 19:25 ` Jens Axboe
2018-12-04 23:37 ` [PATCH 04/26] block: use REQ_HIPRI_ASYNC for non-sync polled IO Jens Axboe
2018-12-04 23:37 ` [PATCH 05/26] iomap: wire up the iopoll method Jens Axboe
2018-12-04 23:37 ` [PATCH 06/26] aio: use assigned completion handler Jens Axboe
2018-12-04 23:37 ` [PATCH 07/26] aio: separate out ring reservation from req allocation Jens Axboe
2018-12-04 23:37 ` [PATCH 08/26] aio: don't zero entire aio_kiocb aio_get_req() Jens Axboe
2018-12-06 19:27 ` Jeff Moyer
2018-12-06 19:28 ` Jens Axboe
2018-12-06 19:38 ` Jeff Moyer
2018-12-06 19:42 ` Jens Axboe
2018-12-04 23:37 ` [PATCH 09/26] aio: only use blk plugs for > 2 depth submissions Jens Axboe
2018-12-06 19:29 ` Jeff Moyer [this message]
2018-12-06 19:31 ` Jens Axboe
2018-12-04 23:37 ` [PATCH 10/26] aio: use iocb_put() instead of open coding it Jens Axboe
2018-12-04 23:37 ` [PATCH 11/26] aio: split out iocb copy from io_submit_one() Jens Axboe
2018-12-04 23:37 ` [PATCH 12/26] aio: abstract out io_event filler helper Jens Axboe
2018-12-04 23:37 ` [PATCH 13/26] aio: add io_setup2() system call Jens Axboe
2018-12-04 23:37 ` [PATCH 14/26] aio: add support for having user mapped iocbs Jens Axboe
2018-12-04 23:37 ` [PATCH 15/26] aio: support for IO polling Jens Axboe
2018-12-05 9:56 ` Benny Halevy
2018-12-05 13:10 ` Jens Axboe
2018-12-06 9:04 ` Benny Halevy
2018-12-04 23:37 ` [PATCH 16/26] aio: add submission side request cache Jens Axboe
2018-12-04 23:37 ` [PATCH 17/26] fs: add fget_many() and fput_many() Jens Axboe
2018-12-04 23:37 ` [PATCH 18/26] aio: use fget/fput_many() for file references Jens Axboe
2018-12-04 23:37 ` [PATCH 19/26] aio: split iocb init from allocation Jens Axboe
2018-12-04 23:37 ` [PATCH 20/26] aio: batch aio_kiocb allocation Jens Axboe
2018-12-04 23:37 ` [PATCH 21/26] block: add BIO_HOLD_PAGES flag Jens Axboe
2018-12-04 23:37 ` [PATCH 22/26] block: implement bio helper to add iter bvec pages to bio Jens Axboe
2018-12-04 23:37 ` [PATCH 23/26] fs: add support for mapping an ITER_BVEC for O_DIRECT Jens Axboe
2018-12-04 23:37 ` [PATCH 24/26] aio: add support for pre-mapped user IO buffers Jens Axboe
2018-12-04 23:37 ` [PATCH 25/26] aio: split old ring complete out from aio_complete() Jens Axboe
2018-12-04 23:37 ` [PATCH 26/26] aio: add support for submission/completion rings Jens Axboe
2018-12-07 18:48 ` [PATCHSET v5] Support for polled aio Jeff Moyer
2018-12-07 18:52 ` Jens Axboe
2018-12-07 18:55 ` Jens Axboe
2018-12-07 19:34 ` Jeff Moyer
2018-12-07 19:35 ` Jens Axboe
2018-12-07 21:58 ` Jens Axboe
2018-12-07 21:59 ` Jens Axboe
2018-12-07 22:00 ` Jens Axboe
2018-12-07 22:06 ` Jens Axboe
-- strict thread matches above, loose matches on Subject: below --
2018-12-07 22:19 [PATCHSET v6] Support for polled aio (and more) Jens Axboe
2018-12-07 22:19 ` [PATCH 09/26] aio: only use blk plugs for > 2 depth submissions Jens Axboe
2018-12-13 17:56 [PATCHSET v8] Support for polled and buffered aio (and more) Jens Axboe
2018-12-13 17:56 ` [PATCH 09/26] aio: only use blk plugs for > 2 depth submissions Jens Axboe
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