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Date: Thu, 26 Apr 2012 17:08:52 +0100 From: Richard Davies <richard.davies@...stichosts.com> To: KOSAKI Motohiro <kosaki.motohiro@...il.com> Cc: Christoph Lameter <cl@...ux.com>, Satoru Moriya <satoru.moriya@....com>, Jerome Marchand <jmarchan@...hat.com>, KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>, "jweiner@...hat.com" <jweiner@...hat.com>, "linux-mm@...ck.org" <linux-mm@...ck.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "riel@...hat.com" <riel@...hat.com>, "lwoodman@...hat.com" <lwoodman@...hat.com>, "shaohua.li@...el.com" <shaohua.li@...el.com>, "dle-develop@...ts.sourceforge.net" <dle-develop@...ts.sourceforge.net>, Seiji Aguchi <seiji.aguchi@....com>, Minchan Kim <minchan.kim@...il.com> Subject: Re: [RFC][PATCH] avoid swapping out with swappiness==0 KOSAKI Motohiro wrote: > Christoph Lameter wrote: > > Richard Davies wrote: > > > > > I strongly believe that Linux should have a way to turn off swapping unless > > > absolutely necessary. This means that users like us can run with swap > > > present for emergency use, rather than having to disable it because of the > > > side effects. > > > > Agree. And this ooperation mode should be the default behavior given that > > swapping is a very slow and tedious process these days. > > Even though current patch is not optimal, I don't disagree this opinion. Can > you please explain your use case? Why don't you use swapoff? My use case is that I have large (64 or 128GB RAM) qemu-kvm virtualization hosts, running many (20-50) VMs. Typically the total memory in use is less than physical memory. In these cases I would like the virtualization host to run without any swapping. I have set swappiness==0, but in practise I get big load spikes from swapping. See http://marc.info/?l=linux-mm&m=133517452117581 I don't want to run swapoff, because sometimes I will need to provision slightly more VMs than physical memory, and in these cases I would rather that the system runs with a little swap in use rather than the OOM killer occurring. Richard. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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