From: Andy Lutomirski <luto@amacapital.net>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Dave Chinner <david@fromorbit.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Benjamin LaHaise <bcrl@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-aio@kvack.org, linux-mm <linux-mm@kvack.org>
Subject: Re: [PATCH 07/13] aio: enabled thread based async fsync
Date: Tue, 12 Jan 2016 14:59:23 -0800 [thread overview]
Message-ID: <CALCETrV0ABY5zZoCNQip0jJOd3gun15v-=s1V+ubm2E7NZDGtA@mail.gmail.com> (raw)
In-Reply-To: <CA+55aFyLb8scNSYb19rK4iT_Vx5=hKxqPwRHVnETzAhEev0aHw@mail.gmail.com>
On Jan 11, 2016 8:04 PM, "Linus Torvalds" <torvalds@linux-foundation.org> wrote:
>
> On Mon, Jan 11, 2016 at 7:37 PM, Dave Chinner <david@fromorbit.com> wrote:
> >
> > Yes, I heard you the first time, but you haven't acknowledged that
> > the aio fsync interface is indeed different because it already
> > exists. What's the problem with implementing an AIO call that we've
> > advertised as supported for many years now that people are asking us
> > to implement it?
>
> Oh, I don't disagree with that. I think it should be exposed, my point
> was that that too was not enough.
>
> I don't see why you argue. You said "that's not enough". And I jjust
> said that your expansion wasn't sufficient either, and that I think we
> should strive to expand things even more.
>
> And preferably not in some ad-hoc manner. Expand it to *everything* we can do.
>
> > As for a generic async syscall interface, why not just add
> > IOCB_CMD_SYSCALL that encodes the syscall number and parameters
> > into the iovec structure and let the existing aio subsystem handle
> > demultiplexing it and handing them off to threads/workqueues/etc?
>
> That would likely be the simplest approach, yes.
>
> There's a few arguments against it, though:
>
> - doing the indirect system call thing does end up being
> architecture-specific, so now you do need the AIO code to call into
> some arch wrapper.
How many arches *can* do it? As of 4.4, x86_32 can, but x86_64 can't
yet. We'd also need a whitelist of acceptable indirect syscalls (e.g.
exit is bad). And we have to worry about things that depend on the mm
or creds.
It would be extra nice if we could avoid switch_mm for things that
don't need it (fsync) and only do it for things like read that do.
--Andy
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next prev parent reply other threads:[~2016-01-12 22:59 UTC|newest]
Thread overview: 51+ 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 ` [PATCH 01/13] signals: distinguish signals sent due to i/o via io_send_sig() Benjamin LaHaise
2016-01-11 22:06 ` [PATCH 02/13] aio: add aio_get_mm() helper Benjamin LaHaise
2016-01-11 22:06 ` [PATCH 03/13] aio: for async operations, make the iter argument persistent Benjamin LaHaise
2016-01-11 22:07 ` [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 ` [PATCH 05/13] fs: make do_loop_readv_writev() non-static 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 ` [PATCH 07/13] aio: enabled thread based async fsync Benjamin LaHaise
2016-01-12 1:11 ` Dave Chinner
2016-01-12 1:20 ` Linus Torvalds
2016-01-12 2:25 ` Dave Chinner
2016-01-12 2:38 ` Linus Torvalds
2016-01-12 3:37 ` Dave Chinner
2016-01-12 4:03 ` Linus Torvalds
2016-01-12 4:48 ` Linus Torvalds
2016-01-12 22:50 ` Benjamin LaHaise
2016-01-15 20:21 ` Benjamin LaHaise
2016-01-20 3:59 ` Linus Torvalds
2016-01-20 5:02 ` Theodore Ts'o
2016-01-20 19:59 ` Dave Chinner
2016-01-20 20:29 ` Linus Torvalds
2016-01-20 20:44 ` Benjamin LaHaise
2016-01-20 21:45 ` Dave Chinner
2016-01-20 21:56 ` Benjamin LaHaise
2016-01-23 4:24 ` Dave Chinner
2016-01-23 4:50 ` Benjamin LaHaise
2016-01-23 22:22 ` Dave Chinner
2016-01-20 23:07 ` Linus Torvalds
2016-01-23 4:39 ` Dave Chinner
2016-03-14 17:17 ` aio openat " Benjamin LaHaise
2016-03-20 1:20 ` Linus Torvalds
2016-03-20 1:26 ` Al Viro
2016-03-20 1:45 ` Linus Torvalds
2016-03-20 1:55 ` Al Viro
2016-03-20 2:03 ` Linus Torvalds
2016-01-20 21:57 ` Dave Chinner
2016-01-22 15:41 ` Andres Freund
2016-01-12 22:59 ` Andy Lutomirski [this message]
2016-01-14 9:19 ` Paolo Bonzini
2016-01-12 1:30 ` Benjamin LaHaise
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 ` [PATCH 09/13] aio: add support for async openat() Benjamin LaHaise
2016-01-12 0:22 ` Linus Torvalds
2016-01-12 1:17 ` Benjamin LaHaise
2016-01-12 1:45 ` Chris Mason
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 ` [PATCH 11/13] mm: enable __do_page_cache_readahead() to include present pages Benjamin LaHaise
2016-01-11 22:07 ` [PATCH 12/13] aio: add support for aio readahead Benjamin LaHaise
2016-01-11 22:08 ` [PATCH 13/13] aio: add support for aio renameat operation Benjamin LaHaise
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