From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1F216C43381 for ; Mon, 18 Feb 2019 16:49:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EEC47217F9 for ; Mon, 18 Feb 2019 16:49:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390168AbfBRQt5 (ORCPT ); Mon, 18 Feb 2019 11:49:57 -0500 Received: from mail-qt1-f193.google.com ([209.85.160.193]:36244 "EHLO mail-qt1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727558AbfBRQt5 (ORCPT ); Mon, 18 Feb 2019 11:49:57 -0500 Received: by mail-qt1-f193.google.com with SMTP id p25so19630572qtb.3 for ; Mon, 18 Feb 2019 08:49:56 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=1KF4cWLuZSrWs0pIbc/fe56fXH4h3PVBY4eBUKkxDcs=; b=AUbEDgITm4INu8K+HJE4/2kyljk7Asbm9CqFZDsc4YfInVkD0bH7tqqRSokLQeaC4q OIbIRyRerFtLD+lgdH0IEwiTmO8g4B+6LBsWvii0JKblZ+vluF/2pFF5h84Ksz8ZQ1Fz W5vclb+VOoXU8oP69wNbCChcY6iAKyDywQTbwhXGkzpJWdAfrJYuf0OCv34Terwf3bWW mQWDyRAZF2s3GfH9WBJ7zaR/vCQ5X5Ak/0wPaGBT+nwf5aUpjF30hM6k6nbJkOZ399VK yy4Uq8pWSBjH8wM7L5rwMuu5uvXc37AiFUmbRtgFQHLnQYYyCU0lW74/vl7vLEYi81vj dURg== X-Gm-Message-State: AHQUAub2ozTxea+95MK/VLmFIUEMKjRxeO/oyj6T54dGSW7ZyAhQRWTO Ux0p68tedQxo35zFKHVFXBt3NA== X-Google-Smtp-Source: AHgI3IZEUAQWaMgS4TmrCSg8g3Pxrkywm/dVrWGPsltVA2gjGpgMc/eBYcCUJG50OEm8buVM3PJVmw== X-Received: by 2002:ac8:365a:: with SMTP id n26mr8714353qtb.18.1550508596281; Mon, 18 Feb 2019 08:49:56 -0800 (PST) Received: from redhat.com (pool-173-76-246-42.bstnma.fios.verizon.net. [173.76.246.42]) by smtp.gmail.com with ESMTPSA id b24sm8393870qta.76.2019.02.18.08.49.54 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 18 Feb 2019 08:49:55 -0800 (PST) Date: Mon, 18 Feb 2019 11:49:53 -0500 From: "Michael S. Tsirkin" To: David Hildenbrand 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 Subject: Re: [RFC][Patch v8 0/7] KVM: Guest Free Page Hinting 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 Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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