From: Al Viro <viro@ZenIV.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Benjamin LaHaise <bcrl@kvack.org>,
Dave Chinner <david@fromorbit.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-aio@kvack.org, linux-mm <linux-mm@kvack.org>
Subject: Re: aio openat Re: [PATCH 07/13] aio: enabled thread based async fsync
Date: Sun, 20 Mar 2016 01:26:10 +0000 [thread overview]
Message-ID: <20160320012610.GX17997@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CA+55aFx7JJdYNWRSs6Nbm_xyQjgUVoBQh=RuNDeavKS1Jr+-ow@mail.gmail.com>
On Sat, Mar 19, 2016 at 06:20:24PM -0700, Linus Torvalds wrote:
> On Mon, Mar 14, 2016 at 10:17 AM, Benjamin LaHaise <bcrl@kvack.org> wrote:
> >
> > I had some time last week to make an aio openat do what it can in
> > submit context. The results are an improvement: when openat is handled
> > in submit context it completes in about half the time it takes compared
> > to the round trip via the work queue, and it's not terribly much code
> > either.
>
> This looks good to me, and I do suspect that any of these aio paths
> should strive to have a synchronous vs threaded model. I think that
> makes the whole thing much more interesting from a performance
> standpoint.
Umm... You do realize that LOOKUP_RCU in flags does *NOT* guarantee that
it won't block, right? At the very least one would need to refuse to
fall back on non-RCU mode without a full restart. Furthermore, vfs_open()
itself can easily block.
So this new LOOKUP flag makes no sense, and it's in the just about _the_
worst place possible for adding special cases with ill-defined semantics -
do_last() is already far too convoluted and needs untangling, not adding
half-assed kludges.
WARNING: multiple messages have this Message-ID (diff)
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Benjamin LaHaise <bcrl@kvack.org>,
Dave Chinner <david@fromorbit.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-aio@kvack.org, linux-mm <linux-mm@kvack.org>
Subject: Re: aio openat Re: [PATCH 07/13] aio: enabled thread based async fsync
Date: Sun, 20 Mar 2016 01:26:10 +0000 [thread overview]
Message-ID: <20160320012610.GX17997@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CA+55aFx7JJdYNWRSs6Nbm_xyQjgUVoBQh=RuNDeavKS1Jr+-ow@mail.gmail.com>
On Sat, Mar 19, 2016 at 06:20:24PM -0700, Linus Torvalds wrote:
> On Mon, Mar 14, 2016 at 10:17 AM, Benjamin LaHaise <bcrl@kvack.org> wrote:
> >
> > I had some time last week to make an aio openat do what it can in
> > submit context. The results are an improvement: when openat is handled
> > in submit context it completes in about half the time it takes compared
> > to the round trip via the work queue, and it's not terribly much code
> > either.
>
> This looks good to me, and I do suspect that any of these aio paths
> should strive to have a synchronous vs threaded model. I think that
> makes the whole thing much more interesting from a performance
> standpoint.
Umm... You do realize that LOOKUP_RCU in flags does *NOT* guarantee that
it won't block, right? At the very least one would need to refuse to
fall back on non-RCU mode without a full restart. Furthermore, vfs_open()
itself can easily block.
So this new LOOKUP flag makes no sense, and it's in the just about _the_
worst place possible for adding special cases with ill-defined semantics -
do_last() is already far too convoluted and needs untangling, not adding
half-assed kludges.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
WARNING: multiple messages have this Message-ID (diff)
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Benjamin LaHaise <bcrl@kvack.org>,
Dave Chinner <david@fromorbit.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-aio@kvack.org, linux-mm <linux-mm@kvack.org>
Subject: Re: aio openat Re: [PATCH 07/13] aio: enabled thread based async fsync
Date: Sun, 20 Mar 2016 01:26:10 +0000 [thread overview]
Message-ID: <20160320012610.GX17997@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CA+55aFx7JJdYNWRSs6Nbm_xyQjgUVoBQh=RuNDeavKS1Jr+-ow@mail.gmail.com>
On Sat, Mar 19, 2016 at 06:20:24PM -0700, Linus Torvalds wrote:
> On Mon, Mar 14, 2016 at 10:17 AM, Benjamin LaHaise <bcrl@kvack.org> wrote:
> >
> > I had some time last week to make an aio openat do what it can in
> > submit context. The results are an improvement: when openat is handled
> > in submit context it completes in about half the time it takes compared
> > to the round trip via the work queue, and it's not terribly much code
> > either.
>
> This looks good to me, and I do suspect that any of these aio paths
> should strive to have a synchronous vs threaded model. I think that
> makes the whole thing much more interesting from a performance
> standpoint.
Umm... You do realize that LOOKUP_RCU in flags does *NOT* guarantee that
it won't block, right? At the very least one would need to refuse to
fall back on non-RCU mode without a full restart. Furthermore, vfs_open()
itself can easily block.
So this new LOOKUP flag makes no sense, and it's in the just about _the_
worst place possible for adding special cases with ill-defined semantics -
do_last() is already far too convoluted and needs untangling, not adding
half-assed kludges.
--
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:[~2016-03-20 1:26 UTC|newest]
Thread overview: 133+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-11 22:06 [PATCH 00/13] aio: thread (work queue) based aio and new aio functionality Benjamin LaHaise
2016-01-11 22:06 ` Benjamin LaHaise
2016-01-11 22:06 ` [PATCH 01/13] signals: distinguish signals sent due to i/o via io_send_sig() Benjamin LaHaise
2016-01-11 22:06 ` Benjamin LaHaise
2016-01-11 22:06 ` Benjamin LaHaise
2016-01-11 22:06 ` [PATCH 02/13] aio: add aio_get_mm() helper Benjamin LaHaise
2016-01-11 22:06 ` Benjamin LaHaise
2016-01-11 22:06 ` Benjamin LaHaise
2016-01-11 22:06 ` [PATCH 03/13] aio: for async operations, make the iter argument persistent Benjamin LaHaise
2016-01-11 22:06 ` Benjamin LaHaise
2016-01-11 22:06 ` Benjamin LaHaise
2016-01-11 22:07 ` [PATCH 04/13] signals: add and use aio_get_task() to direct signals sent via io_send_sig() Benjamin LaHaise
2016-01-11 22:07 ` Benjamin LaHaise
2016-01-11 22:07 ` Benjamin LaHaise
2016-01-11 22:07 ` [PATCH 05/13] fs: make do_loop_readv_writev() non-static Benjamin LaHaise
2016-01-11 22:07 ` Benjamin LaHaise
2016-01-11 22:07 ` Benjamin LaHaise
2016-01-11 22:07 ` [PATCH 06/13] aio: add queue_work() based threaded aio support Benjamin LaHaise
2016-01-11 22:07 ` Benjamin LaHaise
2016-01-11 22:07 ` Benjamin LaHaise
2016-01-11 22:07 ` [PATCH 07/13] aio: enabled thread based async fsync Benjamin LaHaise
2016-01-11 22:07 ` Benjamin LaHaise
2016-01-11 22:07 ` Benjamin LaHaise
2016-01-12 1:11 ` Dave Chinner
2016-01-12 1:11 ` Dave Chinner
2016-01-12 1:20 ` Linus Torvalds
2016-01-12 1:20 ` Linus Torvalds
2016-01-12 2:25 ` Dave Chinner
2016-01-12 2:25 ` Dave Chinner
2016-01-12 2:25 ` Dave Chinner
2016-01-12 2:38 ` Linus Torvalds
2016-01-12 2:38 ` Linus Torvalds
2016-01-12 3:37 ` Dave Chinner
2016-01-12 3:37 ` Dave Chinner
2016-01-12 4:03 ` Linus Torvalds
2016-01-12 4:03 ` Linus Torvalds
2016-01-12 4:48 ` Linus Torvalds
2016-01-12 4:48 ` Linus Torvalds
2016-01-12 22:50 ` Benjamin LaHaise
2016-01-12 22:50 ` Benjamin LaHaise
2016-01-12 22:50 ` Benjamin LaHaise
2016-01-15 20:21 ` Benjamin LaHaise
2016-01-15 20:21 ` Benjamin LaHaise
2016-01-15 20:21 ` Benjamin LaHaise
2016-01-20 3:59 ` Linus Torvalds
2016-01-20 3:59 ` Linus Torvalds
2016-01-20 3:59 ` Linus Torvalds
2016-01-20 5:02 ` Theodore Ts'o
2016-01-20 5:02 ` Theodore Ts'o
2016-01-20 5:02 ` Theodore Ts'o
2016-01-20 19:59 ` Dave Chinner
2016-01-20 19:59 ` Dave Chinner
2016-01-20 19:59 ` Dave Chinner
2016-01-20 20:29 ` Linus Torvalds
2016-01-20 20:29 ` Linus Torvalds
2016-01-20 20:44 ` Benjamin LaHaise
2016-01-20 20:44 ` Benjamin LaHaise
2016-01-20 20:44 ` Benjamin LaHaise
2016-01-20 21:45 ` Dave Chinner
2016-01-20 21:45 ` Dave Chinner
2016-01-20 21:56 ` Benjamin LaHaise
2016-01-20 21:56 ` Benjamin LaHaise
2016-01-20 21:56 ` Benjamin LaHaise
2016-01-23 4:24 ` Dave Chinner
2016-01-23 4:24 ` Dave Chinner
2016-01-23 4:50 ` Benjamin LaHaise
2016-01-23 4:50 ` Benjamin LaHaise
2016-01-23 4:50 ` Benjamin LaHaise
2016-01-23 22:22 ` Dave Chinner
2016-01-23 22:22 ` Dave Chinner
2016-01-23 22:22 ` Dave Chinner
2016-01-20 23:07 ` Linus Torvalds
2016-01-23 4:39 ` Dave Chinner
2016-01-23 4:39 ` Dave Chinner
2016-01-23 4:39 ` Dave Chinner
2016-03-14 17:17 ` aio openat " Benjamin LaHaise
2016-03-14 17:17 ` Benjamin LaHaise
2016-03-20 1:20 ` Linus Torvalds
2016-03-20 1:20 ` Linus Torvalds
2016-03-20 1:26 ` Al Viro [this message]
2016-03-20 1:26 ` Al Viro
2016-03-20 1:26 ` Al Viro
2016-03-20 1:45 ` Linus Torvalds
2016-03-20 1:45 ` Linus Torvalds
2016-03-20 1:45 ` Linus Torvalds
2016-03-20 1:55 ` Al Viro
2016-03-20 1:55 ` Al Viro
2016-03-20 2:03 ` Linus Torvalds
2016-03-20 2:03 ` Linus Torvalds
2016-03-20 2:03 ` Linus Torvalds
2016-01-20 21:57 ` Dave Chinner
2016-01-20 21:57 ` Dave Chinner
2016-01-20 21:57 ` Dave Chinner
2016-01-22 15:41 ` Andres Freund
2016-01-22 15:41 ` Andres Freund
2016-01-12 22:59 ` Andy Lutomirski
2016-01-12 22:59 ` Andy Lutomirski
2016-01-12 22:59 ` Andy Lutomirski
2016-01-14 9:19 ` Paolo Bonzini
2016-01-14 9:19 ` Paolo Bonzini
2016-01-14 9:19 ` Paolo Bonzini
2016-01-12 1:30 ` Benjamin LaHaise
2016-01-12 1:30 ` Benjamin LaHaise
2016-01-12 1:30 ` Benjamin LaHaise
2016-01-22 15:31 ` Andres Freund
2016-01-22 15:31 ` Andres Freund
2016-01-22 15:31 ` Andres Freund
2016-01-11 22:07 ` [PATCH 08/13] aio: add support for aio poll via aio thread helper Benjamin LaHaise
2016-01-11 22:07 ` Benjamin LaHaise
2016-01-11 22:07 ` [PATCH 09/13] aio: add support for async openat() Benjamin LaHaise
2016-01-11 22:07 ` Benjamin LaHaise
2016-01-11 22:07 ` Benjamin LaHaise
2016-01-12 0:22 ` Linus Torvalds
2016-01-12 0:22 ` Linus Torvalds
2016-01-12 1:17 ` Benjamin LaHaise
2016-01-12 1:17 ` Benjamin LaHaise
2016-01-12 1:17 ` Benjamin LaHaise
2016-01-12 1:45 ` Chris Mason
2016-01-12 1:45 ` Chris Mason
2016-01-12 1:45 ` Chris Mason
2016-01-12 9:53 ` Ingo Molnar
2016-01-12 9:53 ` Ingo Molnar
2016-01-12 9:53 ` Ingo Molnar
2016-01-11 22:07 ` [PATCH 10/13] aio: add async unlinkat functionality Benjamin LaHaise
2016-01-11 22:07 ` Benjamin LaHaise
2016-01-11 22:07 ` Benjamin LaHaise
2016-01-11 22:07 ` [PATCH 11/13] mm: enable __do_page_cache_readahead() to include present pages Benjamin LaHaise
2016-01-11 22:07 ` Benjamin LaHaise
2016-01-11 22:07 ` [PATCH 12/13] aio: add support for aio readahead Benjamin LaHaise
2016-01-11 22:07 ` Benjamin LaHaise
2016-01-11 22:08 ` [PATCH 13/13] aio: add support for aio renameat operation Benjamin LaHaise
2016-01-11 22:08 ` Benjamin LaHaise
2016-01-11 22:08 ` Benjamin LaHaise
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