All of lore.kernel.org
 help / color / mirror / Atom feed
From: Andi Kleen <andi@firstfloor.org>
To: Kent Overstreet <koverstreet@google.com>
Cc: linux-kernel@vger.kernel.org,  linux-aio@kvack.org,
	 linux-fsdevel@vger.kernel.org,  zab@redhat.com,  bcrl@kvack.org,
	 jmoyer@redhat.com,  axboe@kernel.dk,  viro@zeniv.linux.org.uk
Subject: Re: [PATCH 22/25] Generic dynamic per cpu refcounting
Date: Thu, 29 Nov 2012 10:45:04 -0800	[thread overview]
Message-ID: <m28v9kgsen.fsf@firstfloor.org> (raw)
In-Reply-To: <1354121029-1376-23-git-send-email-koverstreet@google.com> (Kent Overstreet's message of "Wed, 28 Nov 2012 08:43:46 -0800")

Kent Overstreet <koverstreet@google.com> writes:

> This implements a refcount with similar semantics to
> atomic_get()/atomic_dec_and_test(), that starts out as just an atomic_t
> but dynamically switches to per cpu refcounting when the rate of
> gets/puts becomes too high.

This will only work if you put on the same CPU as you get, right?
In this case I would rather use RCU. It's clearly unusable for anything 
blocking (or not get_cpu) Normally RCU already handles the "ref count for short non
blocking case"

Is that really true for AIO? It seems dubious.

-Andi


-- 
ak@linux.intel.com -- Speaking for myself only

--
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>

WARNING: multiple messages have this Message-ID (diff)
From: Andi Kleen <andi@firstfloor.org>
To: Kent Overstreet <koverstreet@google.com>
Cc: linux-kernel@vger.kernel.org, linux-aio@kvack.org,
	linux-fsdevel@vger.kernel.org, zab@redhat.com, bcrl@kvack.org,
	jmoyer@redhat.com, axboe@kernel.dk, viro@zeniv.linux.org.uk
Subject: Re: [PATCH 22/25] Generic dynamic per cpu refcounting
Date: Thu, 29 Nov 2012 10:45:04 -0800	[thread overview]
Message-ID: <m28v9kgsen.fsf@firstfloor.org> (raw)
In-Reply-To: <1354121029-1376-23-git-send-email-koverstreet@google.com> (Kent Overstreet's message of "Wed, 28 Nov 2012 08:43:46 -0800")

Kent Overstreet <koverstreet@google.com> writes:

> This implements a refcount with similar semantics to
> atomic_get()/atomic_dec_and_test(), that starts out as just an atomic_t
> but dynamically switches to per cpu refcounting when the rate of
> gets/puts becomes too high.

This will only work if you put on the same CPU as you get, right?
In this case I would rather use RCU. It's clearly unusable for anything 
blocking (or not get_cpu) Normally RCU already handles the "ref count for short non
blocking case"

Is that really true for AIO? It seems dubious.

-Andi


-- 
ak@linux.intel.com -- Speaking for myself only

  reply	other threads:[~2012-11-29 18:45 UTC|newest]

Thread overview: 95+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-11-28 16:43 [PATCH 00/25] AIO performance improvements/cleanups Kent Overstreet
2012-11-28 16:43 ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 01/25] mm: remove old aio use_mm() comment Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 02/25] aio: remove dead code from aio.h Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 03/25] gadget: remove only user of aio retry Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 04/25] aio: remove retry-based AIO Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 05/25] char: add aio_{read,write} to /dev/{null,zero} Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 06/25] aio: Kill return value of aio_complete() Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 07/25] aio: kiocb_cancel() Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-29  0:07   ` Zach Brown
2012-11-29  0:58     ` Kent Overstreet
2012-11-29  0:58       ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 08/25] aio: Move private stuff out of aio.h Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 09/25] aio: dprintk() -> pr_debug() Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 10/25] aio: do fget() after aio_get_req() Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 11/25] aio: Make aio_put_req() lockless Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 12/25] aio: Refcounting cleanup Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-29  0:17   ` Zach Brown
2012-11-29  0:17     ` Zach Brown
2012-11-29  1:12     ` Kent Overstreet
2012-11-29  1:12       ` Kent Overstreet
2012-11-29  0:46   ` Benjamin LaHaise
2012-11-29  0:46     ` Benjamin LaHaise
2012-11-29  1:38     ` Kent Overstreet
2012-11-29  1:38       ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 13/25] aio: Convert read_events() to hrtimers Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-29  0:24   ` Zach Brown
2012-11-29  0:24     ` Zach Brown
2012-11-29  1:05     ` Kent Overstreet
2012-11-29  1:05       ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 14/25] aio: Make aio_read_evt() more efficient Kent Overstreet
2012-11-29  0:38   ` Zach Brown
2012-11-29  0:38     ` Zach Brown
2012-11-29 19:31     ` Kent Overstreet
2012-11-29 19:31       ` Kent Overstreet
2012-11-30  0:20     ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 15/25] aio: Use cancellation list lazily Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 16/25] aio: Change reqs_active to include unreaped completions Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 17/25] aio: Kill batch allocation Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 18/25] aio: Kill struct aio_ring_info Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 19/25] aio: Give shared kioctx fields their own cachelines Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 20/25] aio: reqs_active -> reqs_available Kent Overstreet
2012-11-28 16:43 ` [PATCH 21/25] aio: percpu reqs_available Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-28 16:43 ` [PATCH 22/25] Generic dynamic per cpu refcounting Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-29 18:45   ` Andi Kleen [this message]
2012-11-29 18:45     ` Andi Kleen
2012-11-29 18:57     ` Kent Overstreet
2012-11-29 18:57       ` Kent Overstreet
2012-11-29 18:59       ` Andi Kleen
2012-11-29 19:12         ` Kent Overstreet
2012-11-29 19:12           ` Kent Overstreet
2012-11-29 19:20           ` Andi Kleen
2012-11-29 19:20             ` Andi Kleen
2012-11-29 19:29             ` Kent Overstreet
2012-11-29 19:29               ` Kent Overstreet
2012-11-29 19:34               ` Benjamin LaHaise
2012-11-29 19:34                 ` Benjamin LaHaise
2012-11-29 20:22                 ` Kent Overstreet
2012-11-29 20:42                   ` Andi Kleen
2012-11-29 20:45                     ` Kent Overstreet
2012-11-29 20:45                       ` Kent Overstreet
2012-11-29 20:54                       ` Andi Kleen
2012-11-29 20:54                         ` Andi Kleen
2012-11-29 20:59                         ` Kent Overstreet
2012-11-29 21:57                           ` Jamie Lokier
2012-11-29 21:57                             ` Jamie Lokier
2012-11-28 16:43 ` [PATCH 23/25] aio: Percpu ioctx refcount Kent Overstreet
2012-11-28 16:43 ` [PATCH 24/25] aio: use xchg() instead of completion_lock Kent Overstreet
2012-11-28 16:43 ` [PATCH 25/25] aio: Don't include aio.h in sched.h Kent Overstreet
2012-11-28 16:43   ` Kent Overstreet
2012-11-29  0:03 ` [PATCH 00/25] AIO performance improvements/cleanups Zach Brown
2012-11-29  0:03   ` Zach Brown
2012-11-29 19:01   ` Kent Overstreet
2012-11-29 19:01     ` Kent Overstreet
  -- strict thread matches above, loose matches on Subject: below --
2012-11-28  3:19 Kent Overstreet
2012-11-28  3:19 ` [PATCH 22/25] Generic dynamic per cpu refcounting Kent Overstreet

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=m28v9kgsen.fsf@firstfloor.org \
    --to=andi@firstfloor.org \
    --cc=axboe@kernel.dk \
    --cc=bcrl@kvack.org \
    --cc=jmoyer@redhat.com \
    --cc=koverstreet@google.com \
    --cc=linux-aio@kvack.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=viro@zeniv.linux.org.uk \
    --cc=zab@redhat.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.