[PATCH] call mm/page-writeback.c:set_ratelimit() when new pages are hot-added

[PATCH] call mm/page-writeback.c:set_ratelimit() when new pages are hot-added

[Chandra Seetharaman]

ratelimit_pages in page-writeback.c is recalculated (in set_ratelimit())
every time a CPU is hot-added/removed. But this value is not recalculated
when new pages are hot-added.

This patch fixes that problem by calling set_ratelimit() when new pages
are hot-added.

Signed-Off-by: Chandra Seetharaman <sekharan@us.ibm.com>

--
Index: linux-2.6.17/mm/memory_hotplug.c
===================================================================
--- linux-2.6.17.orig/mm/memory_hotplug.c
+++ linux-2.6.17/mm/memory_hotplug.c
@@ -141,6 +141,7 @@ int online_pages(unsigned long pfn, unsi
 	unsigned long start_pfn;
 	struct zone *zone;
 	int need_zonelists_rebuild = 0;
+	extern void set_ratelimit(void);
 
 	/*
 	 * This doesn't need a lock to do pfn_to_page().
@@ -191,6 +192,7 @@ int online_pages(unsigned long pfn, unsi
 	if (need_zonelists_rebuild)
 		build_all_zonelists();
 	vm_total_pages = nr_free_pagecache_pages();
+	set_ratelimit();
 	return 0;
 }
 
Index: linux-2.6.17/mm/page-writeback.c
===================================================================
--- linux-2.6.17.orig/mm/page-writeback.c
+++ linux-2.6.17/mm/page-writeback.c
@@ -490,7 +490,7 @@ void laptop_sync_completion(void)
  * will write six megabyte chunks, max.
  */
 
-static void set_ratelimit(void)
+void set_ratelimit(void)
 {
 	ratelimit_pages = vm_total_pages / (num_online_cpus() * 32);
 	if (ratelimit_pages < 16)

-- 

----------------------------------------------------------------------
    Chandra Seetharaman               | Be careful what you choose....
              - sekharan@us.ibm.com   |      .......you may get it.
----------------------------------------------------------------------


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Re: [PATCH] call mm/page-writeback.c:set_ratelimit() when new pages are hot-added

[Dave Hansen]

On Mon, 2006-08-28 at 15:23 -0700, Chandra Seetharaman wrote:
> --- linux-2.6.17.orig/mm/memory_hotplug.c
> +++ linux-2.6.17/mm/memory_hotplug.c
> @@ -141,6 +141,7 @@ int online_pages(unsigned long pfn, unsi
>         unsigned long start_pfn;
>         struct zone *zone;
>         int need_zonelists_rebuild = 0;
> +       extern void set_ratelimit(void);
>  
>         /*
>          * This doesn't need a lock to do pfn_to_page().
> @@ -191,6 +192,7 @@ int online_pages(unsigned long pfn, unsi
>         if (need_zonelists_rebuild)
>                 build_all_zonelists();
>         vm_total_pages = nr_free_pagecache_pages();
> +       set_ratelimit();
>         return 0;
>  } 

Hi Chandra,

It would be great if you could put set_ratelimit() into a proper header
like the rest of the functions needed by memory hotplug.  These kinds of
externs are ugly because they can too easily get out of sync with their
definitions and cause problems.

-- Dave

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Re: [PATCH] call mm/page-writeback.c:set_ratelimit() when new pages are hot-added

[KAMEZAWA Hiroyuki]

On Mon, 28 Aug 2006 15:23:25 -0700
Chandra Seetharaman <sekharan@us.ibm.com> wrote:

> ratelimit_pages in page-writeback.c is recalculated (in set_ratelimit())
> every time a CPU is hot-added/removed. But this value is not recalculated
> when new pages are hot-added.
> 
> This patch fixes that problem by calling set_ratelimit() when new pages
> are hot-added.
> 

Hi, 
How about adding memory hotplug notifier callbacks (like cpu hotplug) ?
I'll try it if it's worth adding.

-Kame

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