LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Andrea Arcangeli <andrea@qumranet.com>
To: Robin Holt <holt@sgi.com>
Cc: Christoph Lameter <clameter@sgi.com>,
	akpm@linux-foundation.org, Avi Kivity <avi@qumranet.com>,
	Izik Eidus <izike@qumranet.com>,
	kvm-devel@lists.sourceforge.net,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	general@lists.openfabrics.org,
	Steve Wise <swise@opengridcomputing.com>,
	Roland Dreier <rdreier@cisco.com>,
	Kanoj Sarcar <kanojsarcar@yahoo.com>,
	steiner@sgi.com, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, daniel.blueman@quadrics.com
Subject: Re: [PATCH] KVM swapping with MMU Notifiers V7
Date: Mon, 18 Feb 2008 13:35:51 +0100	[thread overview]
Message-ID: <20080218123551.GS11732@v2.random> (raw)
In-Reply-To: <20080216115138.GA11391@sgi.com>

On Sat, Feb 16, 2008 at 05:51:38AM -0600, Robin Holt wrote:
> I am doing this in xpmem with a stack-based structure in the function
> calling get_user_pages.  That structure describes the start and
> end address of the range we are doing the get_user_pages on.  If an
> invalidate_range_begin comes in while we are off to the kernel doing
> the get_user_pages, the invalidate_range_begin marks that structure
> indicating an invalidate came in.  When the get_user_pages gets the
> structures relocked, it checks that flag (really a generation counter)
> and if it is set, retries the get_user_pages.  After 3 retries, it
> returns -EAGAIN and the fault is started over from the remote side.

A seqlock sounds a good optimization for the non-swapping fast path, a
per-VM-guest seqlock number can allow us to know when we need to worry
to call get_user_pages a second time, but won't be really a retry like
in 99% of seqlock usages for the reader side, but just a second
get_user_pages to trigger a minor fault. Then if the page is different
in the second run, we'll really retry (so not in function of the
seqlock but in function of the get_user_pages page array), and there's
no risk of livelocks because get_user_pages returning a different page
won't be the common case. The seqlock should be increased first before
the invalidate and a second time once the invalidate is over.

  reply	other threads:[~2008-02-18 12:36 UTC|newest]

Thread overview: 92+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-15  6:48 [patch 0/6] " Christoph Lameter
2008-02-15  6:49 ` [patch 1/6] mmu_notifier: Core code Christoph Lameter
2008-02-16  3:37   ` Andrew Morton
2008-02-16  8:45     ` Avi Kivity
2008-02-16  8:56       ` Andrew Morton
2008-02-16  9:21         ` Avi Kivity
2008-02-16 10:41     ` Brice Goglin
2008-02-16 10:58       ` Andrew Morton
2008-02-16 19:31         ` Christoph Lameter
2008-02-16 19:21     ` Christoph Lameter
2008-02-17  3:01       ` Andrea Arcangeli
2008-02-17 12:24         ` Robin Holt
2008-02-17  5:04     ` Doug Maxey
2008-02-18 22:33   ` Roland Dreier
2008-02-15  6:49 ` [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges Christoph Lameter
2008-02-16  3:37   ` Andrew Morton
2008-02-16 19:26     ` Christoph Lameter
2008-02-19  8:54   ` Nick Piggin
2008-02-19 13:34     ` Andrea Arcangeli
2008-02-27 22:23       ` Christoph Lameter
2008-02-27 23:57         ` Andrea Arcangeli
2008-02-19 23:08   ` Nick Piggin
2008-02-20  1:00     ` Andrea Arcangeli
2008-02-20  3:00       ` Robin Holt
2008-02-20  3:11         ` Nick Piggin
2008-02-20  3:19           ` Robin Holt
2008-02-27 22:39       ` Christoph Lameter
2008-02-28  0:38         ` Andrea Arcangeli
2008-02-27 22:35     ` Christoph Lameter
2008-02-27 22:42       ` Jack Steiner
2008-02-28  0:10       ` Christoph Lameter
2008-02-28  0:11       ` Andrea Arcangeli
2008-02-28  0:14         ` Christoph Lameter
2008-02-28  0:52           ` Andrea Arcangeli
2008-02-28  1:03             ` Christoph Lameter
2008-02-28  1:10               ` Andrea Arcangeli
2008-02-28 18:43                 ` Christoph Lameter
2008-02-29  0:55                   ` Andrea Arcangeli
2008-02-29  0:59                     ` Christoph Lameter
2008-02-29 13:13                       ` Andrea Arcangeli
2008-02-29 19:55                         ` Christoph Lameter
2008-02-29 20:17                           ` Andrea Arcangeli
2008-02-29 21:03                             ` Christoph Lameter
2008-02-29 21:23                               ` Andrea Arcangeli
2008-02-29 21:29                                 ` Christoph Lameter
2008-02-29 21:34                                 ` Christoph Lameter
2008-02-29 21:48                                   ` Andrea Arcangeli
2008-02-29 22:12                                     ` Christoph Lameter
2008-02-29 22:41                                       ` Andrea Arcangeli
2008-02-28 10:53             ` Robin Holt
2008-03-03  5:11       ` Nick Piggin
2008-03-03 19:28         ` Christoph Lameter
2008-03-03 19:50           ` Nick Piggin
2008-03-04 18:58             ` Christoph Lameter
2008-03-05  0:52               ` Nick Piggin
2008-02-15  6:49 ` [patch 3/6] mmu_notifier: invalidate_page callbacks Christoph Lameter
2008-02-16  3:37   ` Andrew Morton
2008-02-16 11:07     ` Andrea Arcangeli
2008-02-16 19:22     ` Christoph Lameter
2008-02-16 19:54       ` Avi Kivity
2008-02-19  8:46       ` Nick Piggin
2008-02-19 13:30         ` Andrea Arcangeli
2008-02-18  1:51     ` Nick Piggin
2008-02-15  6:49 ` [patch 4/6] mmu_notifier: Skeleton driver for a simple mmu_notifier Christoph Lameter
2008-02-15  6:49 ` [patch 5/6] mmu_notifier: Support for drivers with revers maps (f.e. for XPmem) Christoph Lameter
2008-02-16  3:37   ` Andrew Morton
2008-02-16 19:28     ` Christoph Lameter
2008-02-19 23:55   ` Nick Piggin
2008-02-20  3:12     ` Robin Holt
2008-02-20  3:51       ` Nick Piggin
2008-02-20  9:00         ` Robin Holt
2008-02-20  9:05           ` Robin Holt
2008-02-21  4:20           ` Nick Piggin
2008-02-21 10:58             ` Robin Holt
2008-02-26  6:11               ` Nick Piggin
2008-02-26  7:21                 ` [ofa-general] " Gleb Natapov
2008-02-26  8:52                   ` Nick Piggin
2008-02-26  9:38                     ` Gleb Natapov
2008-02-26  9:52                       ` KOSAKI Motohiro
2008-02-26 12:28                     ` Robin Holt
2008-02-26 12:29                 ` Robin Holt
2008-02-27 22:43     ` Christoph Lameter
2008-02-28  0:42       ` Andrea Arcangeli
2008-02-28  1:01         ` Christoph Lameter
2008-02-15  6:49 ` [patch 6/6] mmu_rmap_notifier: Skeleton for complex driver that uses its own rmaps Christoph Lameter
2008-02-16 10:48 ` [PATCH] KVM swapping with MMU Notifiers V7 Andrea Arcangeli
2008-02-16 11:08   ` Andrew Morton
2008-02-18 12:17     ` Andrea Arcangeli
2008-02-16 11:51   ` Robin Holt
2008-02-18 12:35     ` Andrea Arcangeli [this message]
2008-02-19  8:43 [patch] my mmu notifiers Nick Piggin
2008-02-19 13:58 ` Andrea Arcangeli
2008-02-19 23:11   ` Nick Piggin
2008-02-20  1:09     ` Andrea Arcangeli
2008-02-20 10:39       ` [PATCH] mmu notifiers #v6 Andrea Arcangeli
2008-02-20 10:45         ` [PATCH] KVM swapping (+ seqlock fix) with " Andrea Arcangeli
2008-02-27 22:06           ` [PATCH] KVM swapping with mmu notifiers #v7 Andrea Arcangeli
2008-02-28  8:42             ` izik eidus

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=20080218123551.GS11732@v2.random \
    --to=andrea@qumranet.com \
    --cc=a.p.zijlstra@chello.nl \
    --cc=akpm@linux-foundation.org \
    --cc=avi@qumranet.com \
    --cc=clameter@sgi.com \
    --cc=daniel.blueman@quadrics.com \
    --cc=general@lists.openfabrics.org \
    --cc=holt@sgi.com \
    --cc=izike@qumranet.com \
    --cc=kanojsarcar@yahoo.com \
    --cc=kvm-devel@lists.sourceforge.net \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=rdreier@cisco.com \
    --cc=steiner@sgi.com \
    --cc=swise@opengridcomputing.com \
    --subject='Re: [PATCH] KVM swapping with MMU Notifiers V7' \
    /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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).