linux-kernel - Re: [RFC][PATCH 4/5] memory_pressure

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Message-Id: <20080117120112.11CE.KOSAKI.MOTOHIRO@jp.fujitsu.com>
Date:	Thu, 17 Jan 2008 12:26:58 +0900
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	"Daniel Sp蚣g" 
	<daniel.spang@...il.com>
Cc:	kosaki.motohiro@...fujitsu.com, "Rik van Riel" <riel@...hat.com>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	"Marcelo Tosatti" <marcelo@...ck.org>,
	"Andrew Morton" <akpm@...ux-foundation.org>
Subject: Re: [RFC][PATCH 4/5] memory_pressure_notify() caller

Hi Daniel

> > Thank you for good point out!
> > Could you please post your test program and reproduced method?
> 
> Sure:
> 
> 1. Fill almost all available memory with page cache in a system without swap.
> 2. Run attached alloc-test program.
> 3. Notification fires when page cache is reclaimed.

Unfortunately, I can't reproduce it.

my machine
	CPU:    Pentium4 2.8GHz with HT
	memory: 512M


1. I doubt ZONE_DMA, please shipment ignore zone_dma patch(below).
2. Could you please send your .config and /etc/sysctl.conf?
   I hope more reproduce challenge.

thanks.

- kosaki




Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>

---
 include/linux/mem_notify.h |    3 +++
 mm/page_alloc.c            |    6 +++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

Index: linux-2.6.24-rc6-mm1-memnotify/include/linux/mem_notify.h
===================================================================
--- linux-2.6.24-rc6-mm1-memnotify.orig/include/linux/mem_notify.h
 2008-01-16 21:31:09.000000000 +0900
+++ linux-2.6.24-rc6-mm1-memnotify/include/linux/mem_notify.h
2008-01-16 21:34:24.000000000 +0900
@@ -22,6 +22,9 @@ static inline void memory_pressure_notif
        unsigned long target;
        unsigned long pages_high, pages_free, pages_reserve;

+       if (unlikely(zone->mem_notify_status == -1))
+               return;
+
        if (pressure) {
                target = atomic_long_read(&last_mem_notify) + MEM_NOTIFY_FREQ;
                if (likely(time_before(jiffies, target)))
Index: linux-2.6.24-rc6-mm1-memnotify/mm/page_alloc.c
===================================================================
--- linux-2.6.24-rc6-mm1-memnotify.orig/mm/page_alloc.c 2008-01-13
19:50:27.000000000 +0900
+++ linux-2.6.24-rc6-mm1-memnotify/mm/page_alloc.c      2008-01-16
21:41:58.000000000 +0900
@@ -3467,7 +3467,11 @@ static void __meminit free_area_init_cor
                zone->zone_pgdat = pgdat;

                zone->prev_priority = DEF_PRIORITY;
-               zone->mem_notify_status = 0;
+
+               if (zone->present_pages < (pgdat->node_present_pages / 10))
+                       zone->mem_notify_status = -1;
+               else
+                       zone->mem_notify_status = 0;

                zone_pcp_init(zone);
                INIT_LIST_HEAD(&zone->active_list);



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