Re: [patch v3] swap: virtual swap readahead

Wu Fengguang
2009-06-11T05:22:38Z

On Thu, Jun 11, 2009 at 01:25:16AM +0800, Barnes, Jesse wrote:
> On Wed, 10 Jun 2009 04:32:14 -0700
> "Wu, Fengguang" <fengguang.wu@intel.com> wrote:
>
> > On Wed, Jun 10, 2009 at 06:05:14PM +0800, Peter Zijlstra wrote:
> > > On Wed, 2009-06-10 at 17:59 +0800, Wu Fengguang wrote:
> > > > On Wed, Jun 10, 2009 at 05:42:56PM +0800, Peter Zijlstra wrote:
> > > > > On Wed, 2009-06-10 at 16:56 +0800, Wu Fengguang wrote:
> > > > > >
> > > > > > Yes it worked! But then I run into page allocation failures:
> > > > > >
> > > > > > [ 340.639803] Xorg: page allocation failure. order:4,
> > > > > > mode:0x40d0 [ 340.645744] Pid: 3258, comm: Xorg Not tainted
> > > > > > 2.6.30-rc8-mm1 #303 [ 340.651839] Call Trace:
> > > > > > [ 340.654289] [<ffffffff810c8204>]
> > > > > > __alloc_pages_nodemask+0x344/0x6c0 [ 340.660645]
> > > > > > [<ffffffff810f7489>] __slab_alloc_page+0xb9/0x3b0
> > > > > > [ 340.666472] [<ffffffff810f8608>] __kmalloc+0x198/0x250
> > > > > > [ 340.671786] [<ffffffffa014bf9f>] ?
> > > > > > i915_gem_execbuffer+0x17f/0x11e0 [i915] [ 340.678746]
> > > > > > [<ffffffffa014bf9f>] i915_gem_execbuffer+0x17f/0x11e0 [i915]
> > > > >
> > > > > Jesse Barnes had a patch to add a vmalloc fallback to those
> > > > > largish kms allocs.
> > > > >
> > > > > But order-4 allocs failing isn't really strange, but it might
> > > > > indicate this patch fragments stuff sooner, although I've seen
> > > > > these particular failues before.
> > > >
> > > > Thanks for the tip. Where is it? I'd like to try it out :)
> > >
> > > commit 8e7d2b2c6ecd3c21a54b877eae3d5be48292e6b5
> > > Author: Jesse Barnes <jbarnes@virtuousgeek.org>
> > > Date: Fri May 8 16:13:25 2009 -0700
> > >
> > > drm/i915: allocate large pointer arrays with vmalloc
> >
> > Thanks! It is already in the -mm tree, but it missed on conversion :)
> >
> > I'll retry with this patch tomorrow.
> >
> > Thanks,
> > Fengguang
> > ---
> >
> > diff --git a/drivers/gpu/drm/i915/i915_gem.c
> > b/drivers/gpu/drm/i915/i915_gem.c index 39f5c65..7132dbe 100644
> > --- a/drivers/gpu/drm/i915/i915_gem.c
> > +++ b/drivers/gpu/drm/i915/i915_gem.c
> > @@ -3230,8 +3230,8 @@ i915_gem_execbuffer(struct drm_device *dev,
> > void *data, }
> >
> > if (args->num_cliprects != 0) {
> > - cliprects = drm_calloc(args->num_cliprects,
> > sizeof(*cliprects),
> > - DRM_MEM_DRIVER);
> > + cliprects = drm_calloc_large(args->num_cliprects,
> > + sizeof(*cliprects));
> > if (cliprects == NULL)
> > goto pre_mutex_err;
> >
> > @@ -3474,8 +3474,7 @@ err:
> > pre_mutex_err:
> > drm_free_large(object_list);
> > drm_free_large(exec_list);
> > - drm_free(cliprects, sizeof(*cliprects) * args->num_cliprects,
> > - DRM_MEM_DRIVER);
> > + drm_free_large(cliprects);
> >
> > return ret;
> > }
>
> Kristian posted a fix to my drm_calloc_large function as well; one of
> the size checks in drm_calloc_large (the one which decides whether to
> use kmalloc or vmalloc) was just checking size instead of size * num,
> so you may be hitting that.

Yes, it is.

Unfortunately, after fixing it up the swap readahead patch still performs slow
(even worse this time):

before after
0.02 0.01 N xeyes
0.76 0.89 N firefox
1.88 2.21 N nautilus
3.17 3.41 N nautilus --browser
4.89 5.20 N gthumb
6.47 7.02 N gedit
8.16 8.90 N xpdf /usr/share/doc/shared-mime-info/shared-mime-info-spec.pdf
12.55 13.36 N xterm
14.57 15.57 N mlterm
17.06 18.11 N gnome-terminal
18.90 20.37 N urxvt
23.48 25.26 N gnome-system-monitor
26.52 27.84 N gnome-help
29.65 31.93 N gnome-dictionary
36.12 37.74 N /usr/games/sol
39.27 40.61 N /usr/games/gnometris
42.56 43.75 N /usr/games/gnect
47.03 47.85 N /usr/games/gtali
52.05 52.31 N /usr/games/iagno
55.42 55.61 N /usr/games/gnotravex
61.47 61.38 N /usr/games/mahjongg
67.11 65.07 N /usr/games/gnome-sudoku
75.15 70.36 N /usr/games/glines
79.70 74.96 N /usr/games/glchess
88.48 80.82 N /usr/games/gnomine
96.51 88.30 N /usr/games/gnotski
102.19 94.26 N /usr/games/gnibbles
114.93 102.02 N /usr/games/gnobots2
125.02 115.23 N /usr/games/blackjack
135.11 128.41 N /usr/games/same-gnome
154.50 153.05 N /usr/bin/gnome-window-properties
162.09 169.53 N /usr/bin/gnome-default-applications-properties
173.29 190.32 N /usr/bin/gnome-at-properties
188.21 212.70 N /usr/bin/gnome-typing-monitor
199.93 236.18 N /usr/bin/gnome-at-visual
206.95 261.88 N /usr/bin/gnome-sound-properties
224.49 304.66 N /usr/bin/gnome-at-mobility
234.11 336.73 N /usr/bin/gnome-keybinding-properties
248.59 374.03 N /usr/bin/gnome-about-me
276.27 433.86 N /usr/bin/gnome-display-properties
304.39 488.43 N /usr/bin/gnome-network-preferences
342.01 686.68 N /usr/bin/gnome-mouse-properties
388.58 769.21 N /usr/bin/gnome-appearance-properties
508.47 933.35 N /usr/bin/gnome-control-center
587.57 1193.27 N /usr/bin/gnome-keyboard-properties
[...]

Thanks,
Fengguang