Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!gegeweb.org!de-l.enfer-du-nord.net!feeder1.enfer-du-nord.net!feeds.phibee-telecom.net!usenet.ukfsn.org!not-for-mail From: Martin Gregorie Newsgroups: comp.lang.java.programmer Subject: Re: O.T. optimising file placement Date: Thu, 23 Feb 2012 23:16:28 +0000 (UTC) Organization: UK Free Software Network Lines: 21 Message-ID: References: <3gm7k7lgroqn30g0nd7lqgsqo60hq02em1@4ax.com> <4f45a713$0$291$14726298@news.sunsite.dk> NNTP-Posting-Host: 84.45.235.129 Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Trace: localhost.localdomain 1330038988 8801 84.45.235.129 (23 Feb 2012 23:16:28 GMT) X-Complaints-To: usenet@localhost.localdomain NNTP-Posting-Date: Thu, 23 Feb 2012 23:16:28 +0000 (UTC) User-Agent: Pan/0.135 (Tomorrow I'll Wake Up and Scald Myself with Tea; GIT 30dc37b master) Xref: x330-a1.tempe.blueboxinc.net comp.lang.java.programmer:12287 On Wed, 22 Feb 2012 21:40:19 -0500, Arne Vajhøj wrote: > > Most OS'es support async IO. > Yes, I know, but its not relevant to a single-threaded process since its logic generally requires it to wait for a read or write to complete before it continues[1]. Hence my comment that this prevents head movement being optimized unless a lot of processes are active because there's only one outstanding IOP per process. [1] unless you're deliberately doing async i/o using poll() or select() (in C) or nio (in Java), in which case the process is often best regarded as a half-way house between single and multi-threaded logic. -- martin@ | Martin Gregorie gregorie. | Essex, UK org |