From mboxrd@z Thu Jan 1 00:00:00 1970 From: Con Kolivas Subject: Re: [PATCH] mm: limit lowmem_reserve Date: Thu, 18 May 2006 17:21:38 +1000 References: <200604021401.13331.kernel@kolivas.org> <200605180011.43216.kernel@kolivas.org> <446C1E25.4080408@yahoo.com.au> In-Reply-To: <446C1E25.4080408@yahoo.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200605181721.38735.kernel@kolivas.org> Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Andrew Morton , ck@vds.kolivas.org, linux list , linux-mm@kvack.org List-ID: 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. -- -ck -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org