[PATCH] Zone reclaim: proc override

proc support for zone reclaim

This patch creates a proc entry /proc/sys/vm/zone_reclaim_mode that may be
used to override the automatic determination of the zone reclaim made on
bootup.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 6910c0136f8d7e23458ef0279fbf7b301c3fdd0b..391dd64363e75b560f68bdd69879946b07cf03da 100644 (file)
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -27,6 +27,7 @@ Currently, these files are in /proc/sys/vm:
 - laptop_mode
 - block_dump
 - drop-caches
 - laptop_mode
 - block_dump
 - drop-caches

+- zone_reclaim_mode

 
 ==============================================================
 
 
 ==============================================================
 


@@ -120,3 +121,20 @@ set to pcp->high/4.  The upper limit of batch is (PAGE_SHIFT * 8)
 
 The initial value is zero.  Kernel does not use this value at boot time to set
 the high water marks for each per cpu page list.
 
 The initial value is zero.  Kernel does not use this value at boot time to set
 the high water marks for each per cpu page list.

+
+===============================================================
+
+zone_reclaim_mode:
+
+This is set during bootup to 1 if it is determined that pages from
+remote zones will cause a significant performance reduction. The
+page allocator will then reclaim easily reusable pages (those page
+cache pages that are currently not used) before going off node.
+
+The user can override this setting. It may be beneficial to switch
+off zone reclaim if the system is used for a file server and all
+of memory should be used for caching files from disk.
+
+It may be beneficial to switch this on if one wants to do zone
+reclaim regardless of the numa distances in the system.
+

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 7f472127b7b59d2d3a85e99b15ffea69f670e071..8352a7ce58951673caff4da3f1a7468d77445fc2 100644 (file)
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -182,6 +182,7 @@ enum
        VM_SWAP_TOKEN_TIMEOUT=28, /* default time for token time out */
        VM_DROP_PAGECACHE=29,   /* int: nuke lots of pagecache */
        VM_PERCPU_PAGELIST_FRACTION=30,/* int: fraction of pages in each percpu_pagelist */
        VM_SWAP_TOKEN_TIMEOUT=28, /* default time for token time out */
        VM_DROP_PAGECACHE=29,   /* int: nuke lots of pagecache */
        VM_PERCPU_PAGELIST_FRACTION=30,/* int: fraction of pages in each percpu_pagelist */

+       VM_ZONE_RECLAIM_MODE=31,/* reclaim local zone memory before going off node */

 };
 
 
 };
 
 

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index f5d69b6e29f50fb051b8ecf1add5964865c105f4..cb99a42f8b37c60e991332ce33b4fba1dacb9dc6 100644 (file)
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -869,6 +869,17 @@ static ctl_table vm_table[] = {
                .proc_handler   = &proc_dointvec_jiffies,
                .strategy       = &sysctl_jiffies,
        },
                .proc_handler   = &proc_dointvec_jiffies,
                .strategy       = &sysctl_jiffies,
        },

+#endif
+#ifdef CONFIG_NUMA
+       {
+               .ctl_name       = VM_ZONE_RECLAIM_MODE,
+               .procname       = "zone_reclaim_mode",
+               .data           = &zone_reclaim_mode,
+               .maxlen         = sizeof(zone_reclaim_mode),
+               .mode           = 0644,
+               .proc_handler   = &proc_dointvec,
+               .strategy       = &zero,
+       },

 #endif
        { .ctl_name = 0 }
 };
 #endif
        { .ctl_name = 0 }
 };