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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Ben Greear <greearb@candelatech.com>
Cc: NetDev <netdev@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Tejun Heo <tj@kernel.org>
Subject: Re: OOM when adding ipv6 route:  How to make available more per-cpu memory?
Date: Fri, 05 Nov 2010 23:11:43 +0100	[thread overview]
Message-ID: <1288995103.2665.653.camel@edumazet-laptop> (raw)
In-Reply-To: <1288988403.2665.268.camel@edumazet-laptop>

Le vendredi 05 novembre 2010 à 21:20 +0100, Eric Dumazet a écrit :
> Your vmalloc space is very fragmented. pcpu_get_vm_areas() want
> hugepages (4MB on your machine, 2MB on mine because I have
> CONFIG_HIGHMEM64G=y)

Well, this is wrong. We use normal (4KB) pages, unfortunately.

I have a NUMA machine, with two nodes, so pcpu_get_vm_areas() allocates
two zones, one for each node, with a 'known' offset between them.
Then, 4KB pages are allocated to populate the zone when needed.

# grep pcpu_get_vm_areas /proc/vmallocinfo 
0xffffe8ffa0400000-0xffffe8ffa0600000 2097152 pcpu_get_vm_areas+0x0/0x740 vmalloc
0xffffe8ffffc00000-0xffffe8ffffe00000 2097152 pcpu_get_vm_areas+0x0/0x740 vmalloc

BTW, we dont have the number of pages currently allocated in each
'vmalloc' zone, and/or node information.

Tejun, do you have plans to use hugepages eventually ?
(and fallback to 4KB pages, but most percpu data are allocated right
after boot)

Thanks



  parent reply	other threads:[~2010-11-05 22:11 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-11-05 17:19 OOM when adding ipv6 route: How to make available more per-cpu memory? Ben Greear
2010-11-05 18:06 ` Eric Dumazet
2010-11-05 18:15   ` Ben Greear
2010-11-05 20:20     ` Eric Dumazet
2010-11-05 20:26       ` Ben Greear
2010-11-05 20:53         ` Eric Dumazet
2010-11-05 22:11       ` Eric Dumazet [this message]
2010-11-06  0:07         ` Ben Greear
2010-11-06  7:26           ` Eric Dumazet
2010-11-06 17:08             ` Ben Greear
2010-11-08 11:02               ` Eric Dumazet
2010-11-08 17:45                 ` Ben Greear
2010-11-08 17:55                   ` Eric Dumazet
2010-11-08 18:08                     ` Ben Greear
2010-11-08 21:27                 ` Ben Greear
2010-11-08 21:40                   ` Eric Dumazet
2010-11-06  9:11         ` Tejun Heo

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