Re: Linux rocks
Steve Browne <[email protected]>
| Newsgroups | gmane.org.user-groups.nmlug |
|---|---|
| Message-ID | <[email protected]> |
On Mon, 26 Mar 2007 21:37:14 -0600, you wrote: >Just thought I'd share some stuff that happened today. > >I just finished moving a LAMP(php/perl) stack over from a Pentium 4 3.4GHz/1GB >RAM machine to a Pentium D 3.4/2GB RAM server. There was about 1.5GB of >data in the MySQL database, and the client had a long running query that >would aggregate much of it and display it on a page. It would normally take >about 20-30 seconds to run. > >After moving over the scripts and database, the client tested the script, >and as expected, it ran only slightly faster than it did on the other >machine. Then the client wanted to run two instances of the script and see >how the dual core system handled it. He started one, but before he could >start the second, the first one was complete. He was pretty concerned, >thinking that something much have been broken by the move, and that a cached >copy was being served. How could a 30 second query be served in less than a >second? > >A quick look at "free -m" showed that although the OS and LAMP stack was >only taking 95MB of RAM, over 1.5GB was being used as cache. The majority >of the normal 30 second query time was spent reading the data off disk. >After the first query, Linux cached all the database files in RAM, so the >next time the queries didn't have to pull anything off disk. That combined >with MySQL's query cache made a big difference. The client was pretty >impressed. > >The moral? >Linux's aggressive file system caching is a good thing (usually). >Linux doesn't let unused RAM sit around doing nothing, and sometimes it >shows in a big way. So, if you can afford it, go for more RAM. If you use a multipurpose system, that presents some problems. If you have a legacy WinME shared installation, it won't run in more than 1.5Gb. RAM. If you have a shared XP installation, it won't run in more than 4Gb. RAM. For a while Hiren's BootCD (FreeDOS) balked at more than 2Gb. RAM, but the latest release (v8.9) has fixed that. Moral: dump Windows, though DOS can still be handy. Steve Stephen B. Browne [email protected] "Ubi bene, ibi patria." _______________________________________________ NMLUG mailing list [email protected] http://lists.b9.com/cgi-bin/mailman/listinfo/nmlug