From: Pavel Machek <pavel@ucw.cz>
To: Matthew Dobson <colpatch@us.ibm.com>
Cc: Chris Wright <chrisw@osdl.org>,
linux-kernel@vger.kernel.org,
Linux Memory Management <linux-mm@kvack.org>
Subject: Re: [RFC][PATCH 0/8] Critical Page Pool
Date: Sat, 10 Dec 2005 08:39:15 +0000 [thread overview]
Message-ID: <20051210083915.GB2833@ucw.cz> (raw)
In-Reply-To: <439616B6.1020308@us.ibm.com>
Hi!
> > ...and then you find out that your test was not "bad enough" or that
> > it needs more memory on different machines. It may be good enough hack
> > for your usage, but I do not think it belongs in mainline.
> > Pavel
>
> Way late in responding to this, but...
>
> Apropriate sizing of this pool is a known issue. For example, we want to
> use it to keep the networking stack alive during extreme memory pressure
> situations. The only way to size the pool so as to *guarantee* that it
> will not be exhausted during the 2 minute window we need would be to ensure
> that the pool has at least (TOTAL_BANDWITH_OF_ALL_NICS * 120 seconds) bytes
> available. In the case of a simple system with a single GigE adapter we'd
> need (1 gigbit/sec * 120 sec) = 120 gigabits = 15 gigabytes of reserve
> pool. That is obviously completely impractical, considering many boxes
And it is not enough... If someone hits you with small packets,
allocation overhead is going to be high.
Pavel
--
Thanks, Sharp!
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next prev parent reply other threads:[~2005-12-10 8:39 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-18 19:32 Matthew Dobson
2005-11-18 19:36 ` [RFC][PATCH 1/8] Create " Matthew Dobson
2005-11-19 0:08 ` Paul Jackson
2005-11-21 5:50 ` Matthew Dobson
2005-11-21 5:54 ` Paul Jackson
2005-11-18 19:36 ` [RFC][PATCH 2/8] Create emergency trigger Matthew Dobson
2005-11-19 0:21 ` Paul Jackson
2005-11-21 5:51 ` Matthew Dobson
2005-11-18 19:40 ` [RFC][PATCH 3/8] Slab cleanup Matthew Dobson
2005-11-18 19:41 ` [RFC][PATCH 4/8] Fix a bug in scsi_get_command Matthew Dobson
2005-11-18 19:43 ` [RFC][PATCH 5/8] get_object/return_object Matthew Dobson
2005-11-18 19:44 ` [RFC][PATCH 6/8] slab_destruct Matthew Dobson
2005-11-18 19:44 ` [RFC][PATCH 0/8] Critical Page Pool Avi Kivity
2005-11-18 19:51 ` Matthew Dobson
2005-11-18 20:42 ` Avi Kivity
2005-11-19 0:10 ` Paul Jackson
2005-11-21 5:36 ` Matthew Dobson
2005-11-18 19:45 ` [RFC][PATCH 7/8] __cache_grow() Matthew Dobson
2005-11-18 19:47 ` [RFC][PATCH 8/8] Add support critical pool support to the slab allocator Matthew Dobson
2005-11-18 19:56 ` [RFC][PATCH 0/8] Critical Page Pool Chris Wright
2005-11-21 5:47 ` Matthew Dobson
2005-11-21 13:29 ` Pavel Machek
2005-12-06 22:54 ` Matthew Dobson
2005-12-10 8:39 ` Pavel Machek [this message]
2005-11-20 7:45 ` Keith Owens
2005-11-21 5:53 ` Matthew Dobson
2005-11-20 23:04 ` Pavel Machek
2005-11-21 5:58 ` Matthew Dobson
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