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,URIBL_BLOCKED autolearn=unavailable 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 26004C43444 for ; Thu, 10 Jan 2019 23:12:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F2FF7213F2 for ; Thu, 10 Jan 2019 23:12:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728292AbfAJXMv (ORCPT ); Thu, 10 Jan 2019 18:12:51 -0500 Received: from mx1.redhat.com ([209.132.183.28]:38968 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726149AbfAJXMu (ORCPT ); Thu, 10 Jan 2019 18:12:50 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id AB8368E66F; Thu, 10 Jan 2019 23:12:50 +0000 (UTC) Received: from segfault.boston.devel.redhat.com (segfault.boston.devel.redhat.com [10.19.60.26]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E1D1760C67; Thu, 10 Jan 2019 23:12:49 +0000 (UTC) From: Jeff Moyer To: Jens Axboe Cc: linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, linux-block@vger.kernel.org, linux-arch@vger.kernel.org, hch@lst.de, avi@scylladb.com Subject: Re: [PATCH 15/15] io_uring: add io_uring_event cache hit information References: <20190110024404.25372-1-axboe@kernel.dk> <20190110024404.25372-16-axboe@kernel.dk> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 Date: Thu, 10 Jan 2019 18:12:49 -0500 In-Reply-To: <20190110024404.25372-16-axboe@kernel.dk> (Jens Axboe's message of "Wed, 9 Jan 2019 19:44:04 -0700") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Thu, 10 Jan 2019 23:12:50 +0000 (UTC) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Message-ID: <20190110231249.AChwqkbcujgJddSVpuBY4-hzjv1Eva5gnRSXnOsOqYE@z> Jens Axboe writes: > Add hint on whether a read was served out of the page cache, or if it > hit media. This is useful for buffered async IO, O_DIRECT reads would > never have this set (for obvious reasons). > > If the read hit page cache, cqe->flags will have IOCQE_FLAG_CACHEHIT > set. We may want to hold off on this one until the whole mincore/RWF_NOWAIT debate is sorted. [1] Cheers, Jeff [1] https://lore.kernel.org/lkml/20190109022430.GE27534@dastard/