From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [RFC][Patch v8 0/7] KVM: Guest Free Page Hinting Date: Mon, 18 Feb 2019 11:49:53 -0500 Message-ID: <20190218114601-mutt-send-email-mst@kernel.org> References: <20190204201854.2328-1-nitesh@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Nitesh Narayan Lal , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, pbonzini@redhat.com, lcapitulino@redhat.com, pagupta@redhat.com, wei.w.wang@intel.com, yang.zhang.wz@gmail.com, riel@surriel.com, dodgen@google.com, konrad.wilk@oracle.com, dhildenb@redhat.com, aarcange@redhat.com, Alexander Duyck To: David Hildenbrand Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Sat, Feb 16, 2019 at 10:40:15AM +0100, David Hildenbrand wrote: > It would be worth a try. My feeling is that a synchronous report after > e.g. 512 frees should be acceptable, as it seems to be acceptable on > s390x. (basically always enabled, nobody complains). What slips under the radar on an arch like s390 might raise issues for a popular arch like x86. My fear would be if it's only a problem e.g. for realtime. Then you get a condition that's very hard to trigger and affects worst case latencies. But really what business has something that is supposedly an optimization blocking a VCPU? We are just freeing up lots of memory why is it a good idea to slow that process down? -- MST