From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH 15/15] io_uring: add io_uring_event cache hit information Date: Thu, 10 Jan 2019 16:47:28 -0700 Message-ID: References: <20190110024404.25372-1-axboe@kernel.dk> <20190110024404.25372-16-axboe@kernel.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Sender: owner-linux-aio@kvack.org To: Jeff Moyer 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 List-Id: linux-arch.vger.kernel.org On 1/10/19 4:12 PM, Jeff Moyer wrote: > 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] Definitely, it's why it's separate and at the end of the series. But in reality, this doesn't leak anything that timing doesn't already tell you. So it's kind of a moot point. -- Jens Axboe -- To unsubscribe, send a message with 'unsubscribe linux-aio' in the body to majordomo@kvack.org. For more info on Linux AIO, see: http://www.kvack.org/aio/ Don't email: aart@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-f193.google.com ([209.85.215.193]:42043 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728702AbfAJXrd (ORCPT ); Thu, 10 Jan 2019 18:47:33 -0500 Received: by mail-pg1-f193.google.com with SMTP id d72so5484238pga.9 for ; Thu, 10 Jan 2019 15:47:33 -0800 (PST) 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> From: Jens Axboe Message-ID: Date: Thu, 10 Jan 2019 16:47:28 -0700 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Jeff Moyer 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 Message-ID: <20190110234728.dulNsx6FmhabGotUgoEjHLqOlXEvDL2WrCnIYqdIkoU@z> On 1/10/19 4:12 PM, Jeff Moyer wrote: > 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] Definitely, it's why it's separate and at the end of the series. But in reality, this doesn't leak anything that timing doesn't already tell you. So it's kind of a moot point. -- Jens Axboe