linux-kernel - Re: [PATCH 1/3] A device for zero-copy based on KVM virtio-net.

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Message-ID: <20100406074901.GB9662@redhat.com>
Date:	Tue, 6 Apr 2010 10:49:02 +0300
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	"Xin, Xiaohui" <xiaohui.xin@...el.com>
Cc:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"mingo@...e.hu" <mingo@...e.hu>,
	"jdike@...user-mode-linux.org" <jdike@...user-mode-linux.org>,
	"yzhao81@...il.com" <yzhao81@...il.com>
Subject: Re: [PATCH 1/3] A device for zero-copy based on KVM virtio-net.

On Tue, Apr 06, 2010 at 01:41:37PM +0800, Xin, Xiaohui wrote:
> Michael,
> >> 
> >>For the DOS issue, I'm not sure how much the limit get_user_pages()
> >> can pin is reasonable, should we compute the bindwidth to make it?
> 
> >There's a ulimit for locked memory. Can we use this, decreasing
> >the value for rlimit array? We can do this when backend is
> >enabled and re-increment when backend is disabled.
> 
> I have tried it with rlim[RLIMIT_MEMLOCK].rlim_cur, but I found
> the initial value for it is 0x10000, after right shift PAGE_SHIFT,
> it's only 16 pages we can lock then, it seems too small, since the 
> guest virito-net driver may submit a lot requests one time.
> 
> 
> Thanks
> Xiaohui

Yes, that's the default, but system administrator can always increase
this value with ulimit if necessary.

-- 
MST
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