From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Con Kolivas <kernel@kolivas.org>
Cc: Andrew Morton <akpm@osdl.org>,
ck@vds.kolivas.org, linux list <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org
Subject: Re: [PATCH] mm: limit lowmem_reserve
Date: Thu, 18 May 2006 17:26:09 +1000 [thread overview]
Message-ID: <446C2191.70300@yahoo.com.au> (raw)
In-Reply-To: <200605181721.38735.kernel@kolivas.org>
Con Kolivas wrote:
> On Thursday 18 May 2006 17:11, Nick Piggin wrote:
>
>>If we're under memory pressure, kswapd will try to free up any candidate
>>zone, yes.
>>
>>
>>>On my test case this indeed happens and my ZONE_DMA never goes below 3000
>>>pages free. If I lower the reserve even further my pages free gets stuck
>>>at 3208 and can't free any more, and doesn't ever drop below that either.
>>>
>>>Here is the patch I was proposing
>>
>>What problem does that fix though?
>
>
> It's a generic concern and I honestly don't know how significant it is which
> is why I'm asking if it needs attention. That concern being that any time
> we're under any sort of memory pressure, ZONE_DMA will undergo intense
> reclaim even though there may not really be anything specifically going on in
> ZONE_DMA. It just seems a waste of cycles doing that.
>
If it doesn't have any/much pagecache or slab cache in it, there won't be
intense reclaim; if it does then it can be reclaimed and the memory used.
reclaim / allocation could be slightly smarter about scaling watermarks,
however I don't think it is much of an issue at the moment.
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
prev parent reply other threads:[~2006-05-18 7:26 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-04-02 4:01 2.6.16-ck3 Con Kolivas
2006-04-02 4:46 ` 2.6.16-ck3 Nick Piggin
2006-04-02 8:51 ` 2.6.16-ck3 Con Kolivas
2006-04-02 9:37 ` 2.6.16-ck3 Nick Piggin
2006-04-02 9:39 ` [ck] 2.6.16-ck3 Con Kolivas
2006-04-02 9:51 ` Nick Piggin
2006-04-03 2:48 ` lowmem_reserve question Con Kolivas
2006-04-03 4:42 ` Mike Galbraith
2006-04-03 4:48 ` Con Kolivas
2006-04-03 4:50 ` [ck] " Con Kolivas
2006-04-03 5:14 ` Mike Galbraith
2006-04-03 5:18 ` Con Kolivas
2006-04-03 5:31 ` Mike Galbraith
2006-04-04 2:35 ` [ck] " Con Kolivas
2006-04-06 1:10 ` [PATCH] mm: limit lowmem_reserve Con Kolivas
2006-04-06 1:29 ` Respin: " Con Kolivas
2006-04-06 2:43 ` Andrew Morton
2006-04-06 2:55 ` Con Kolivas
2006-04-06 2:58 ` Con Kolivas
2006-04-06 3:40 ` Andrew Morton
2006-04-06 4:36 ` Con Kolivas
2006-04-06 4:52 ` Con Kolivas
2006-04-07 6:25 ` Nick Piggin
2006-04-07 9:02 ` Con Kolivas
2006-04-07 12:40 ` Nick Piggin
2006-04-08 0:15 ` Con Kolivas
2006-04-08 0:55 ` Nick Piggin
2006-04-08 1:01 ` Con Kolivas
2006-04-08 1:25 ` Nick Piggin
2006-05-17 14:11 ` Con Kolivas
2006-05-18 7:11 ` Nick Piggin
2006-05-18 7:21 ` Con Kolivas
2006-05-18 7:26 ` Nick Piggin [this message]
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