From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [PATCH] KVM: Defer remote tlb flushes on invlpg (v4)
Date: Mon, 20 Apr 2009 15:01:43 +0200
Message-ID: <20090420130142.GD15228@random.random>
References: <1237468666-30700-1-git-send-email-avi@redhat.com> <49CF4F11.30804@redhat.com> <20090411164853.GH1329@random.random> <20090412223158.GA31408@amt.cnet> <20090418153427.GB15228@random.random> <20090419175428.GB28197@amt.cnet>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: Avi Kivity <avi@redhat.com>, kvm@vger.kernel.org
To: Marcelo Tosatti <mtosatti@redhat.com>
Return-path: <kvm-owner@vger.kernel.org>
Received: from mx2.redhat.com ([66.187.237.31]:41563 "EHLO mx2.redhat.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1754238AbZDTNBt (ORCPT <rfc822;kvm@vger.kernel.org>);
	Mon, 20 Apr 2009 09:01:49 -0400
Received: from int-mx2.corp.redhat.com (int-mx2.corp.redhat.com [172.16.27.26])
	by mx2.redhat.com (8.13.8/8.13.8) with ESMTP id n3KD1j7R028811
	for <kvm@vger.kernel.org>; Mon, 20 Apr 2009 09:01:45 -0400
Content-Disposition: inline
In-Reply-To: <20090419175428.GB28197@amt.cnet>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

On Sun, Apr 19, 2009 at 02:54:28PM -0300, Marcelo Tosatti wrote:
> I'm fine with your kvm_flush_local_tlb. Just one minor nit:
> 
> +   /* get new asid before returning to guest mode */
> +   if (!test_bit(KVM_REQ_TLB_FLUSH, &vcpu->requests))
> +               set_bit(KVM_REQ_TLB_FLUSH, &vcpu->requests);
> 
> Whats the test_bit for?

To avoid a write in case it was already set... but thinking twice I
guess the probability that it's already set is near zero, so I'll
remove it and I'll just do set_bit.

> It was nice to hide explicit knowledge about
> vcpu->kvm->remote_tlbs_dirty behind the interface instead of exposing
> it.

Hmm ok, if you prefer it I'll add it back. I guess ..._tlb_dirty_cond
is better name so it's clear it's not just checking the cond but the
dirty flag too.