Path: csiph.com!x330-a1.tempe.blueboxinc.net!newsfeed.hal-mli.net!feeder3.hal-mli.net!newsfeed.hal-mli.net!feeder1.hal-mli.net!weretis.net!feeder1.news.weretis.net!news.albasani.net!.POSTED!not-for-mail From: Lew Newsgroups: comp.lang.java.programmer Subject: Re: O.T. optimising file placement Date: Fri, 24 Feb 2012 10:50:39 -0800 Organization: albasani.net Lines: 53 Message-ID: References: <3gm7k7lgroqn30g0nd7lqgsqo60hq02em1@4ax.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: news.albasani.net zU/8BwKQduO87sFAfqNsdzKuAUzyK890xk7scb/JdxFHPvh1gbjQWCdTkhnReyw8fJNzPQQnQiJ7F6VHmwUsda5CEOGmlC5SI95U4+WsnSLRq1FbMjPHb6LOzRZe+Sew NNTP-Posting-Date: Fri, 24 Feb 2012 18:50:40 +0000 (UTC) Injection-Info: news.albasani.net; logging-data="lbL4sxt/u5lFP3P+R8DmuFESzwcB05Km66vC4ztbjCJnE+vK7QSV+d2Wj+plVSjOa3352X1cvdsmr85qDgSVzyZ3wJMy4ZmPux0a6oSzuD+1n6bF51nUVOPd5HgU6N60"; mail-complaints-to="abuse@albasani.net" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.2) Gecko/20120216 Thunderbird/10.0.2 In-Reply-To: Cancel-Lock: sha1:BIu9Rf02iiYT1XoWsUgmaMT+Mig= Xref: x330-a1.tempe.blueboxinc.net comp.lang.java.programmer:12293 Martin Gregorie wrote: > Unlike some, I take a good deal of interest in what my machines are up > to, so I was quoting what I see using top on my Linux systems. During > normal operation there is very little activity on my laptop except from > the programs I'm actively using unless, as you say, logwatch/smartd/ > rkhunter/updatedb get run by atd, but on a reasonably quick machine they > don't run for long. > > Of course, the house server is a different case, since it has several > 24/7 services on it, but again its only heavy, continuous disk activity > is overnight when it runs backups/logwatch/smartd/updatedb. Apart from > that requests that wake up Postfix/Spamassassin/Apache/or ftpd/sshd are > pretty sporadic and the disk LED flashes are best described as > intermittent. Sounds like disk optimizations would help that system. > The longest continuously busy time on either machine is during backups > and even there there precious little contention since rsync or tar+gzip > since the only stuff being written to the disk its reading from are > backup logs. Same applies to software update sessions. To the best of my > knowledge (and watching top) none of yum, rpm, tar, gzip or rsync are > multi-threaded: rsync is probably using poll() based async i/o but from > top and observed behaviour none of the others seem to do that. In fact > the only long-running programs on my systems that I know to be multi- > threaded are Apache, Postgres, SA and Postfix. Now /that/ is objective evidence. In your particular case you have no need of optimization of your disk processes. You don't mention it but by omission I will grant you that virtual memory on your system does not seriously contend for disk either. But a typical consumer scenario is to listen to a stream while surfing the web on Windows with several chat windows open, causing multiple disk IO ops on a constant basis of themselves and also putting pressure on virtual memory. Even such a single-user system can benefit from elevator seeking and on-disk buffers. Consider also that burstiness of demand does not argue against the need for optimization, really. During bursts the optimization helps, and a user might complain if their disks got weird once an hour. Regardless, if you don't need optimization why worry? It's like the Pope comparing brands of condoms. Again, we don't excoriate the value of optimizations by citing examples where optimization isn't needed. We evaluate optimizations by how useful they are when they are needed. -- Lew Honi soit qui mal y pense. http://upload.wikimedia.org/wikipedia/commons/c/cf/Friz.jpg