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?
> command:
> %echo 0 > /proc/sys/vm/better_locality
Who could resist having better locality? ;)
> Will rebuild zonelist in following order.
>
> Node(0)'s NORMAL -> Node(1)'s NORMAL -> Node(0)'s DMA.
>
> if set better_locality == 1 (default), zonelist is
> Node(0)'s NORMAL -> Node(0)'s DMA -> Node(1)'s NORMAL.
>
> Maybe useful in some users with heavy memory pressure and mlocks.
>
> ...
>
> 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.
> /* 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.
> + .procname = "better_locality",
> + .data = &sysctl_better_locality,
> + .maxlen = sizeof(sysctl_better_locality),
> + .mode = 0644,
> + .proc_handler = &sysctl_better_locality_handler,
> + .strategy = &sysctl_intvec,
> + },
>
> ..
>
> +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.
> @@ -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.
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