On Tue, 6 Jul 2004, Jeremy Zawodny wrote: > > procs memory page disks faults cpu > > r b w avm fre flt re pi po fr sr da0 md0 in sy cs us sy > > > > 0 13 0 782108 61388 748 0 0 0 863 0 13 0 399 3756 276 23 95 > > 2 13 0 788184 59172 2350 0 0 0 1394 0 73 0 424 7918 1142 29 90 > > Wow. > > If I've reassembled your vmstat output correctly, you're burning A LOT > of system time. :-(
You read it right. Lots. > Well, I've seen machines witth cs numbers at lest 20 times that high > and they were still getting some work done. (It was part of a MyQSL > benchmark I ran, in fact.) Interesting. I'm not really more than about 70% sure of what a "context switch" is, my best read of it is that it's bad when those numbers go up because the scheduler is inefficiently juggling process around in the run queue... > Yeah, you're not doing much I/O at all. Hmm. Yep, hmmm indeed. :) > Well, they're really apples and oranges. But I think you problem is > *not* MySQL. It sounds as though you still have trouble with > LinuxThreads, so I'd look at qmail. I'd try tracing (via truss) some > of qmail's procs to see what they heck they're doing. Maybe they're > needlessly making A LOT of syscalls? I've worked with some much larger qmail installs, and the brick wall we hit in scaling it up is very similar; the box just seems to drown in syscalls. I think this is a "feature" of qmail; even if you're not very familiar with it, the basic gist is that a message goes from process to process rather than having a monolithic process like sendmail. At some point, I'm thinking this just doesn't scale well (we had trouble doing more than 2000 or so concurrent remote deliveries on a dual xeon box). > No, the memory is almost all shared, so memory overhead isn't an > issue. Excellent, that's very good to know. > > -Most queries are simple selects to grab user info (check password, check > > "homedir"). > > Using the query cache at all? Not sure... I'm using the values for caches and whatnot from the my-large.cnf in the distribution. > > Also, out of curiousity, the db servers that you've mentioned Yahoo is > > running are all likely dedicated mysql boxes, right?No dual-purpose > > stuff, correct? > > That's accurate for the majority of servers, yes. But not because > apache and MySQL don't co-habitate well. It's because the raito of > "apache machines" to "mysql machines" needed is rarely 1:1. Yeah, I was just hoping to find someone with a similar setup to see how their box is behaving. > You'd think, yeah. I don't know squat about qmail, having moved from > Sendmail to Exim a few years back. Maybe it really hammers systems? Apparently. I've started playing with Postfix a bit more and I find it to be much nicer than qmail. But for the foreseeable future I'm stuck with qmail. If I feel real brave I'll raise the syscall issue on the qmail list. Thanks again, Charles > Jeremy > -- > Jeremy D. Zawodny | Perl, Web, MySQL, Linux Magazine, Yahoo! > <[EMAIL PROTECTED]> | http://jeremy.zawodny.com/ > > [book] High Performance MySQL -- http://highperformancemysql.com/ > -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
