From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Moyer Subject: Re: [RFC v2 0/5] Non-blockling buffered fs read (page cache only) Date: Mon, 22 Sep 2014 10:24:16 -0400 Message-ID: References: <20140919104204.3b0bb762@lwn.net> <20140922101221.4bf46809@lwn.net> Mime-Version: 1.0 Content-Type: text/plain Cc: Milosz Tanski , LKML , Christoph Hellwig , "linux-fsdevel\@vger.kernel.org" , linux-aio@kvack.org, Mel Gorman , Volker Lendecke , Tejun Heo , "Theodore Ts'o" , Al Viro To: Jonathan Corbet Return-path: In-Reply-To: <20140922101221.4bf46809@lwn.net> (Jonathan Corbet's message of "Mon, 22 Sep 2014 10:12:21 -0400") Sender: owner-linux-aio@kvack.org List-Id: linux-fsdevel.vger.kernel.org Jonathan Corbet writes: > On Fri, 19 Sep 2014 13:33:14 -0400 > Milosz Tanski wrote: > >> > - Non-blocking I/O has long been supported with a well-understood set >> > of operations - O_NONBLOCK and fcntl(). Why do we need a different >> > mechanism here - one that's only understood in the context of >> > buffered file I/O? I assume you didn't want to implement support >> > for poll() and all that, but is that a good enough reason to add a >> > new Linux-specific non-blocking I/O technique? >> >> I realized that I didn't answer this question well in my other long >> email. O_NONBLOCK doesn't work on files under any commonly used OS, >> and people have gotten use to this behavior so I doubt we could change >> that without breaking a lot of folks applications. > > So I'm not contesting this, but I am genuinely curious: do you think > there are applications out there requesting non-blocking behavior on > regular files that will then break if they actually get non-blocking > behavior? I don't suppose you have an example? Hi, Jon, Back when I tried to introduct O_NONBLOCK for regular files, the squid proxy actually broke. Software that dealt with burning optical media also broke. See my mail message here for more details: https://lkml.org/lkml/2014/9/15/942 Cheers, Jeff -- 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