From: Christoph Hellwig <hch@lst.de>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>,
viro@zeniv.linux.org.uk, Avi Kivity <avi@scylladb.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-aio@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/4] aio: allow direct aio poll comletions for keyed wakeups
Date: Wed, 8 Aug 2018 11:57:19 +0200 [thread overview]
Message-ID: <20180808095719.GA20653@lst.de> (raw)
In-Reply-To: <20180807090441.67f7e281f502ce448de849c1@linux-foundation.org>
On Tue, Aug 07, 2018 at 09:04:41AM -0700, Andrew Morton wrote:
> > Because it is faster obviously. I can update the comment.
>
> I meant the comment could explain why it's a trylock instead of a
> spin_lock().
We could something like this the patch below.
Al, do you want me to resend or can you just fold it in?
diff --git a/fs/aio.c b/fs/aio.c
index 5943098a87c6..84df2c2bf80b 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1684,7 +1684,8 @@ static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
/*
* Try to complete the iocb inline if we can to avoid a costly
- * context switch.
+ * context switch. As the waitqueue lock nests inside the ctx
+ * lock we can only do that if we can get it without waiting.
*/
if (spin_trylock(&iocb->ki_ctx->ctx_lock)) {
list_del(&iocb->ki_list);
next prev parent reply other threads:[~2018-08-08 9:51 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-06 8:30 aio poll V22 (aka 2.0) Christoph Hellwig
2018-08-06 8:30 ` [PATCH 1/4] timerfd: add support for keyed wakeups Christoph Hellwig
2018-08-06 8:30 ` [PATCH 2/4] aio: add a iocb refcount Christoph Hellwig
2018-08-06 8:30 ` [PATCH 3/4] aio: implement IOCB_CMD_POLL Christoph Hellwig
2018-08-06 8:30 ` [PATCH 4/4] aio: allow direct aio poll comletions for keyed wakeups Christoph Hellwig
2018-08-06 22:27 ` Andrew Morton
2018-08-07 7:25 ` Christoph Hellwig
2018-08-07 16:04 ` Andrew Morton
2018-08-08 9:57 ` Christoph Hellwig [this message]
2018-08-07 11:44 ` [PATCH 4/4 v2] " Christoph Hellwig
2018-08-06 16:49 ` aio poll V22 (aka 2.0) Linus Torvalds
2018-08-07 7:27 ` Christoph Hellwig
-- strict thread matches above, loose matches on Subject: below --
2018-07-30 7:15 aio poll and a new in-kernel poll API V21 " Christoph Hellwig
2018-07-30 7:15 ` [PATCH 4/4] aio: allow direct aio poll comletions for keyed wakeups Christoph Hellwig
2018-07-26 8:28 aio poll and a new in-kernel poll API V20 (aka 2.0) Christoph Hellwig
2018-07-26 8:29 ` [PATCH 4/4] aio: allow direct aio poll comletions for keyed wakeups Christoph Hellwig
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