Re: Pgsql (and mysql) benchmark on T2000/Solaris and some
От | Arjen van der Meijden |
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Тема | Re: Pgsql (and mysql) benchmark on T2000/Solaris and some |
Дата | |
Msg-id | 4469D986.6090300@tweakers.net обсуждение исходный текст |
Ответ на | Re: Pgsql (and mysql) benchmark on T2000/Solaris and some ("Jignesh K. Shah" <J.K.Shah@Sun.COM>) |
Ответы |
Re: Pgsql (and mysql) benchmark on T2000/Solaris and some
("Jignesh K. Shah" <J.K.Shah@Sun.COM>)
|
Список | pgsql-performance |
Hi Jignesh, Jignesh K. Shah wrote: > Hi Arjen, > > Looking at your outputs...of syscall and usrcall it looks like > > * Spending too much time in semsys .... which means you have too many > connections and they are contending to get a lock.. which is potentially > the WAL log lock > > * llseek is high which means you can obviously gain a bit with the right > file system/files tuning by caching them right. > > Have you set the values for Solaris for T2000 tuned for Postgresql? Not particularly, we got a "special T2000 Solaris dvd" from your colleagues here in the Netherlands and installed that (actually one of your colleagues did). Doing so all the "better default" /etc/system-settings are supposed to be set. I haven't really checked that they are, since two of your colleagues have been working on it for the mysql-version of the benchmark and I assumed they'd have verified that. > Check out the tunables from the following URL > > http://www.sun.com/servers/coolthreads/tnb/applications_postgresql.jsp > > Try specially the /etc/system and postgresql.conf changes and see if it > changes/improves your performance. I will see that those tunables are verified to be set. I am a bit surprised though about your remarks, since they'd point at the I/O being in the way? But we only have about 600k/sec i/o according to vmstat. The database easily fits in memory. In total I logged about 500k queries of which only 70k where altering queries, of which almost all where inserts in log-tables which aren't actively read in this benchmark. But I'll give it a try. Best regards, Arjen > > Arjen van der Meijden wrote: >> Hi List, >> >> In the past few weeks we have been developing a read-heavy >> mysql-benchmark to have an alternative take at >> cpu/platform-performance. Not really to have a look at how fast mysql >> can be. >> >> This benchmark runs on mysql 4.1.x, 5.0.x and 5.1.x and is modelled >> after our website's production database and the load generated on it >> is modelled after a simplified version of our visitor behaviour. >> >> Long story short, we think the test is a nice example of the >> relatively lightweight, read-heavy webapplications out there and >> therefore decided to have a go at postgresql as well. >> Of course the queries and indexes have been adjusted to (by our >> knowledge) best suit postgresql, while maintaining the same output to >> the application/interface layer. While the initial structure only got >> postgresql at about half the performance of mysql 4.1.x, the current >> version of our postgresql-benchmark has quite similar results to mysql >> 4.1.x, but both are quite a bit slower than 5.0.x (I think its about >> 30-40% faster). >> >> Since the results from those benchmarks are not yet public (they will >> be put together in a story at our website), I won't go into too much >> details about this benchmark. >> >> Currently we're having a look at a Sun T2000 and will be looking at >> will be looking at other machines as well in the future. We are >> running the sun-release of postgresql 8.1.3 on that T2000 now, but are >> looking at compiling the cvs-head version (for its index-root-cache) >> somewhere this week. >> >> My guess is there are a few people on this list who are interested in >> some dtrace results taken during our benchmarks on that T2000. >> Although my knowledge of both Solaris and Dtrace are very limited, I >> already took some samples of the system and user calls. I used Jignesh >> Shah's scripts for that: >> http://blogs.sun.com/roller/page/jkshah?entry=profiling_postgresql_using_dtrace_on >> >> >> You can find the samples here: >> http://achelois.tweakers.net/~acm/pgsql-t2000/syscall.log >> http://achelois.tweakers.net/~acm/pgsql-t2000/usrcall.log >> >> And I also did the memcpy-scripts, here: >> http://achelois.tweakers.net/~acm/pgsql-t2000/memcpysize.log >> http://achelois.tweakers.net/~acm/pgsql-t2000/memcpystack.log >> (this last log is 3.5MB) >> >> If anyone is interested in some more dtrace results, let me know (and >> tell me what commands to run ;-) ). >> >> Best regards, >> >> Arjen >> >> ---------------------------(end of broadcast)--------------------------- >> TIP 3: Have you checked our extensive FAQ? >> >> http://www.postgresql.org/docs/faq > > ---------------------------(end of broadcast)--------------------------- > TIP 6: explain analyze is your friend >
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