[PATCH 11/20] aio: only use blk plugs for > 2 depth submissions
From: Jens Axboe <axboe@kernel.dk>
Date: 2018-11-27 03:40:48
Also in:
linux-fsdevel
Subsystem:
aio, filesystems (vfs and infrastructure), the rest · Maintainers:
Benjamin LaHaise, Alexander Viro, Christian Brauner, Linus Torvalds
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. 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 681f2072f81b..533cb7b1112f 100644
--- a/fs/aio.c
+++ b/fs/aio.c@@ -1887,6 +1887,12 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, return ret; } +/* + * 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 + /* sys_io_submit: * Queue the nr iocbs pointed to by iocbpp for processing. Returns * the number of iocbs queued. May return -EINVAL if the aio_context
@@ -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;
--
2.17.1