On Wed, 25 Apr 2007 00:42:14 -0700
Andrew Morton <[EMAIL PROTECTED]> wrote:
> On Wed, 25 Apr 2007 12:19:46 +0900 KAMEZAWA Hiroyuki <[EMAIL PROTECTED]>
> wrote:
>
> > Make zonelist policy selectable from sysctl.
> >
> > Assume 2 node NUMA, only node(0) has ZONE_DMA (ZONE_DMA32).
> >
> > In this case, default (node0's) zonelist order is
> >
> > Node(0)'s NORMAL -> Node(0)'s DMA -> Node(1)"s NORMAL.
> >
> > This means Node(0)'s DMA is used before Node(1)'s NORMAL.
> >
> > In some server, some application uses large memory allcation.
> > This exhaust memory in the above order.
> > Then....sometimes OOM_KILL will occur when 32bit device requires memory.
> >
> > This patch adds sysctl for rebuilding zonelist after boot and doesn't change
> > default zonelist order.
>
> hm. Why don't we use that ordering all the time? Does the present ordering
> have
> any advantage?
>
I don't know ;) maybe some high-end NUMA hardware has IOMMU and
zoning by memory address has no meaning.
> > command:
> > %echo 0 > /proc/sys/vm/better_locality
>
> Who could resist having better locality? ;)
>
how about changing this name to strict_zone_order and
if strict_zone_order = 1
Node(0)'NORMAL -> Node(1)'Normal -> Node(0)'DMA
if strict_zone_order = 0
Node(0)'NORMAL -> Node(0)'DMA -> Node(1)'NORMAL
If someone thinks of better name, please teach me.
> > extern int percpu_pagelist_fraction;
> > extern int compat_log;
> > +#ifdef CONFIG_NUMA
> > +extern int sysctl_better_locality;
> > +#endif
>
> The ifdef isn't needed here. If something went wrong, we'll find out at
> link-time.
>
Okay.
> > /* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and
> > GID */
> > static int maxolduid = 65535;
> > @@ -845,6 +848,15 @@ static ctl_table vm_table[] = {
> > .extra1 = &zero,
> > .extra2 = &one_hundred,
> > },
> > + {
> > + .ctl_name = VM_BETTER_LOCALITY,
>
> Please don't add new sysctls: use CTL_UNNUMBERED here.
>
Oh, I didn't know about CTL_UNNUMBERED. looks useful. I'll try.
> > +static void build_zonelists(pg_data_t *pgdat)
> > +{
> > + if (sysctl_better_locality) {
> > + build_zonelists_locality_aware(pgdat);
> > + } else {
> > + build_zonelists_zone_aware(pgdat);
> > + }
>
> Remove all the braces please.
Okay.
>
> > @@ -207,6 +207,7 @@ enum
> > VM_PANIC_ON_OOM=33, /* panic at out-of-memory */
> > VM_VDSO_ENABLED=34, /* map VDSO into new processes? */
> > VM_MIN_SLAB=35, /* Percent pages ignored by zone reclaim */
> > + VM_BETTER_LOCALITY=36, /* create locality-preference zonelist */
>
> This can go away.
>
Okay.
I'll wait for other replies and post updated one tomorrow.
Thank you,
-Kame
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