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From: Matthew Dobson <colpatch@us.ibm.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Andrea Arcangeli <andrea@suse.de>, Pavel Machek <pavel@suse.cz>,
	linux-kernel@vger.kernel.org, Sridhar Samudrala <sri@us.ibm.com>,
	Andrew Morton <akpm@osdl.org>,
	Linux Memory Management <linux-mm@kvack.org>
Subject: Re: [RFC][PATCH 0/6] Critical Page Pool
Date: Wed, 14 Dec 2005 08:37:12 -0800	[thread overview]
Message-ID: <43A04A38.6020403@us.ibm.com> (raw)
In-Reply-To: <1134565436.25663.24.camel@localhost.localdomain>

Alan Cox wrote:
> On Mer, 2005-12-14 at 13:01 +0100, Andrea Arcangeli wrote:
> 
>>On Wed, Dec 14, 2005 at 11:08:41AM +0100, Pavel Machek wrote:
>>
>>>because reserved memory pool would have to be "sum of all network
>>>interface bandwidths * ammount of time expected to survive without
>>>network" which is way too much.
>>
>>Yes, a global pool isn't really useful. A per-subsystem pool would be
>>more reasonable...
> 
> 
> 
> The whole extra critical level seems dubious in itself. In 2.0/2.2 days
> there were a set of patches that just dropped incoming memory on sockets
> when the memory was tight unless they were marked as critical (ie NFS
> swap). It worked rather well. The rest of the changes beyond that seem
> excessive.

Actually, Sridhar's code (mentioned earlier in this thread) *does* drop
incoming packets that are not 'critical', but unfortunately you need to
completely copy the packet into kernel memory before you can do any
processing on it to determine whether or not it's 'critical', and thus
accept or reject it.  If network traffic is coming in at a good clip and
the system is already under memory pressure, it's going to be difficult to
receive all these packets, which was the inspiration for this patchset.

Thanks!

-Matt

  reply	other threads:[~2005-12-14 16:37 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-12-14  7:50 [RFC][PATCH 0/6] Critical Page Pool Matthew Dobson
2005-12-14  7:52 ` [RFC][PATCH 1/6] Create " Matthew Dobson
2005-12-14 10:48   ` Andrea Arcangeli
2005-12-14 13:30   ` Rik van Riel
2005-12-14 16:26     ` Matthew Dobson
2005-12-15  3:29       ` Matt Mackall
2005-12-14  7:54 ` [RFC][PATCH 2/6] in_emergency Trigger Matthew Dobson
2005-12-14  7:56 ` [RFC][PATCH 3/6] Slab Prep: get/return_object Matthew Dobson
2005-12-14  8:19   ` Pekka Enberg
2005-12-14 16:26     ` Matthew Dobson
2005-12-14  7:58 ` [RFC][PATCH 4/6] Slab Prep: slab_destruct() Matthew Dobson
2005-12-14  8:37   ` Pekka Enberg
2005-12-14 16:30     ` Matthew Dobson
2005-12-14  7:59 ` [RFC][PATCH 5/6] Slab Prep: Move cache_grow() Matthew Dobson
2005-12-14  8:02 ` [RFC][PATCH 6/6] Critical Page Pool: Slab Support Matthew Dobson
2005-12-14 10:08 ` [RFC][PATCH 0/6] Critical Page Pool Pavel Machek
2005-12-14 12:01   ` Andrea Arcangeli
2005-12-14 13:03     ` Alan Cox
2005-12-14 16:37       ` Matthew Dobson [this message]
2005-12-14 19:17         ` Alan Cox
2005-12-15 16:27         ` Pavel Machek
2005-12-14 16:03     ` Matthew Dobson
2005-12-14 15:55   ` Matthew Dobson
2005-12-15 16:26     ` Pavel Machek
2005-12-15 21:51       ` Matthew Dobson
2005-12-16  5:02         ` Sridhar Samudrala

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