* [PATCH] io_uring: Try to merge io requests only for regular files
@ 2021-03-19 5:28 Dmitry Monakhov
2021-03-19 6:36 ` Greg KH
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: Dmitry Monakhov @ 2021-03-19 5:28 UTC (permalink / raw)
To: linux-kernel; +Cc: linux-fsdevel, stable, axboe, Dmitry Monakhov
Otherwise we may endup blocking on pipe or socket.
Fixes: 6d5d5ac ("io_uring: extend async work merge")
Testcase: https://github.com/dmonakhov/liburing/commit/16d171b6ef9d68e6db66650a83d98c5c721d01f6
Signed-off-by: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>
---
fs/io_uring.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 478df7e..848657c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2183,6 +2183,9 @@ static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
static struct async_list *io_async_list_from_req(struct io_ring_ctx *ctx,
struct io_kiocb *req)
{
+ if (!(req->flags & REQ_F_ISREG))
+ return NULL;
+
switch (req->submit.opcode) {
case IORING_OP_READV:
case IORING_OP_READ_FIXED:
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] io_uring: Try to merge io requests only for regular files
2021-03-19 5:28 [PATCH] io_uring: Try to merge io requests only for regular files Dmitry Monakhov
@ 2021-03-19 6:36 ` Greg KH
2021-03-19 7:45 ` Dmitry Monakhov
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Greg KH @ 2021-03-19 6:36 UTC (permalink / raw)
To: Dmitry Monakhov; +Cc: linux-kernel, linux-fsdevel, stable, axboe
On Fri, Mar 19, 2021 at 05:28:59AM +0000, Dmitry Monakhov wrote:
> Otherwise we may endup blocking on pipe or socket.
>
> Fixes: 6d5d5ac ("io_uring: extend async work merge")
> Testcase: https://github.com/dmonakhov/liburing/commit/16d171b6ef9d68e6db66650a83d98c5c721d01f6
> Signed-off-by: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>
> ---
> fs/io_uring.c | 3 +++
> 1 file changed, 3 insertions(+)
<formletter>
This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.
</formletter>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] io_uring: Try to merge io requests only for regular files
2021-03-19 5:28 [PATCH] io_uring: Try to merge io requests only for regular files Dmitry Monakhov
2021-03-19 6:36 ` Greg KH
@ 2021-03-19 7:45 ` Dmitry Monakhov
2021-03-19 10:23 ` Pavel Begunkov
2021-03-19 14:06 ` Matthew Wilcox
3 siblings, 0 replies; 5+ messages in thread
From: Dmitry Monakhov @ 2021-03-19 7:45 UTC (permalink / raw)
To: linux-kernel; +Cc: linux-fsdevel, axboe
[-- Attachment #1: Type: text/plain, Size: 1311 bytes --]
- stable@
19.03.2021, 08:29, "Dmitry Monakhov" <dmtrmonakhov@yandex-team.ru>:
> Otherwise we may endup blocking on pipe or socket.
>
> Fixes: 6d5d5ac ("io_uring: extend async work merge")
> Testcase: https://github.com/dmonakhov/liburing/commit/16d171b6ef9d68e6db66650a83d98c5c721d01f6
> Signed-off-by: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>
> ---
> fs/io_uring.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 478df7e..848657c 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -2183,6 +2183,9 @@ static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
> static struct async_list *io_async_list_from_req(struct io_ring_ctx *ctx,
> struct io_kiocb *req)
> {
> + if (!(req->flags & REQ_F_ISREG))
> + return NULL;
> +
IMHO it is reasonable to completely disable io_should_merge logic because
even with the this fix it still affected by latency spikes like follows:
->submit_read: req1[slow_hdd, sector=z]
->submit_read: req2[nvme, sector=X]
-> wait(req2) -> fast
->submit_read: req3[nvme, sector=Y]
--> wait(req3) ->slow
if completes if X and Y belongs to same page merge logic will wait for req1 to complete
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: 0001-io_uring-completely-disable-io_should_merge-logic.patch --]
[-- Type: text/x-diff; name="0001-io_uring-completely-disable-io_should_merge-logic.patch", Size: 780 bytes --]
From c24cda9aa902775e4e23575b758f009e9fae4640 Mon Sep 17 00:00:00 2001
From: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>
Date: Fri, 19 Mar 2021 08:48:18 +0300
Subject: [PATCH] io_uring: completely disable io_should_merge logic
io_should_merge logic is wierd and prone to latency spikes because of slow neighbors.
Signed-off-by: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 478df7e..a4fb3a7 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1288,7 +1288,7 @@ static ssize_t io_import_iovec(struct io_ring_ctx *ctx, int rw,
static inline bool io_should_merge(struct async_list *al, struct kiocb *kiocb)
{
- if (al->file == kiocb->ki_filp) {
+ if (al->file == kiocb->ki_filp && 0) {
off_t start, end;
/*
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] io_uring: Try to merge io requests only for regular files
2021-03-19 5:28 [PATCH] io_uring: Try to merge io requests only for regular files Dmitry Monakhov
2021-03-19 6:36 ` Greg KH
2021-03-19 7:45 ` Dmitry Monakhov
@ 2021-03-19 10:23 ` Pavel Begunkov
2021-03-19 14:06 ` Matthew Wilcox
3 siblings, 0 replies; 5+ messages in thread
From: Pavel Begunkov @ 2021-03-19 10:23 UTC (permalink / raw)
To: Dmitry Monakhov, linux-kernel; +Cc: linux-fsdevel, stable, axboe, io-uring
On 19/03/2021 05:28, Dmitry Monakhov wrote:
> Otherwise we may endup blocking on pipe or socket.
CC: io-uring ml
>
> Fixes: 6d5d5ac ("io_uring: extend async work merge")
> Testcase: https://github.com/dmonakhov/liburing/commit/16d171b6ef9d68e6db66650a83d98c5c721d01f6
> Signed-off-by: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>
> ---
> fs/io_uring.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 478df7e..848657c 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -2183,6 +2183,9 @@ static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
> static struct async_list *io_async_list_from_req(struct io_ring_ctx *ctx,
> struct io_kiocb *req)
> {
> + if (!(req->flags & REQ_F_ISREG))
> + return NULL;
> +
> switch (req->submit.opcode) {
> case IORING_OP_READV:
> case IORING_OP_READ_FIXED:
>
--
Pavel Begunkov
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] io_uring: Try to merge io requests only for regular files
2021-03-19 5:28 [PATCH] io_uring: Try to merge io requests only for regular files Dmitry Monakhov
` (2 preceding siblings ...)
2021-03-19 10:23 ` Pavel Begunkov
@ 2021-03-19 14:06 ` Matthew Wilcox
3 siblings, 0 replies; 5+ messages in thread
From: Matthew Wilcox @ 2021-03-19 14:06 UTC (permalink / raw)
To: Dmitry Monakhov; +Cc: linux-kernel, linux-fsdevel, stable, axboe
On Fri, Mar 19, 2021 at 05:28:59AM +0000, Dmitry Monakhov wrote:
> Otherwise we may endup blocking on pipe or socket.
>
> Fixes: 6d5d5ac ("io_uring: extend async work merge")
7 bytes of sha1 isn't enough. You can set core.abbrev to 12 or upgrade
to a version of git from this decade to get that automatically.
> 2.7.4
... is from 2016, so you're five years out of date. Don't get cut
off when git switches from SHA1.
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-03-19 14:07 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2021-03-19 5:28 [PATCH] io_uring: Try to merge io requests only for regular files Dmitry Monakhov
2021-03-19 6:36 ` Greg KH
2021-03-19 7:45 ` Dmitry Monakhov
2021-03-19 10:23 ` Pavel Begunkov
2021-03-19 14:06 ` Matthew Wilcox
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