From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH] Using the tlb flush util function where applicable
Date: Wed, 17 Sep 2014 13:06:02 +0200
Message-ID: <54196B1A.3000208@redhat.com>
References: <1410556005-15639-1-git-send-email-liangchen.linux@gmail.com> <20140915193351.GA3356@potion.brq.redhat.com> <20140917001524.GA11326@kernel> <20140917104551.GA31476@potion.brq.redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: QUOTED-PRINTABLE
Cc: Liang Chen <liangchen.linux@gmail.com>, kvm@vger.kernel.org
To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
	Wanpeng Li <wanpeng.li@linux.intel.com>
Return-path: <kvm-owner@vger.kernel.org>
Received: from mx1.redhat.com ([209.132.183.28]:61234 "EHLO mx1.redhat.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1754118AbaIQLGJ (ORCPT <rfc822;kvm@vger.kernel.org>);
	Wed, 17 Sep 2014 07:06:09 -0400
In-Reply-To: <20140917104551.GA31476@potion.brq.redhat.com>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

Il 17/09/2014 12:45, Radim Kr=C4=8Dm=C3=A1=C5=99 ha scritto:
>  a) count local KVM_REQ_TLB_FLUSH requests
>  b) count all TLB flushes
>  c) both (a) and (b)
>=20
> I was thinking that when you look at /sys/kernel/debug/kvm/tlb_flushe=
s,
> you are interested in the number of TLB flushes that VMs did, not
> requests, so you won't have to add remote_tlb_flushes multiplied by
> maximal vcpu count and guess their amount from this upper bound.

I agree.  The difference isn't too big, but if two requests are
coalesced they will only cause a hit once.

Paolo

> And that we don't even care about requests, so (c) is just complicati=
on.