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Message-ID: <4E565704.5080007@redhat.com> Date: Thu, 25 Aug 2011 17:07:00 +0300 From: Avi Kivity <avi@...hat.com> To: Marcelo Tosatti <mtosatti@...hat.com> CC: Xiao Guangrong <xiaoguangrong@...fujitsu.com>, LKML <linux-kernel@...r.kernel.org>, KVM <kvm@...r.kernel.org> Subject: Re: [PATCH 11/11] KVM: MMU: improve write flooding detected On 08/25/2011 05:06 PM, Avi Kivity wrote: > On 08/25/2011 04:21 PM, Marcelo Tosatti wrote: >> On Thu, Aug 25, 2011 at 07:42:10AM +0300, Avi Kivity wrote: >> > On 08/25/2011 05:04 AM, Marcelo Tosatti wrote: >> > >> >> > >> It could increase the flood count independently of the >> accessed bit of >> > >> the spte being updated, zapping after 3 attempts as it is now. >> > >> >> > >> But additionally reset the flood count if the gpte appears to >> be valid >> > >> (points to an existant gfn if the present bit is set, or if >> its zeroed). >> > > >> > >Well not zero, as thats a common pattern for non ptes. >> > > >> > >> > On 32-bit with 4GB RAM, practically anything is a valid gpte. >> >> The following could be required to consider a valid gpte, for write >> flood detection purposes: >> >> - Must be present. >> - PageCacheDisable must be unset. >> - PageWriteThrough must be unset. >> > > Unless the guest is using PAT. > And not swapping. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain. -- 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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