[nycbug-talk] Re: MySQL
lists at zaunere.com
Mon Aug 22 20:50:26 EDT 2005
Francisco Reyes wrote on Monday, August 22, 2005 3:22 PM:
> On Sun, 21 Aug 2005, Hans Zaunere wrote:
> > Try turning on query caching.
> That alone has been very helpfull. Utilization was 50% to 70% and was
> doing mostly 20 to 70 queries/second. Now utilization is
> mostly under 40%
> and QPS is 40 to 120 QPS.
> > But before any of that, get the right binary. The number one
> > problem with MySQL on FreeBSD is that people use the wrong binary.
> I will eventually try that. I see is as a riskier proposition. The cache
> setting is a win win (little risk, performance increase, cpu
> utilization reduction).
Ehh, well - watch MySQL on a four-way SMP FreeBSD 4.7 box and come back to
You can skirt around the right binary, but especially when you start getting
higher concurrencies, it won't be fun. There's little fuss/risk, but do be
aware of MySQL's version changes (noteably 4.0 -> 4.1).
> Any suggestions on values for the cache size? Started at 64K, then 128K
> now at 256K.
All depends on the schema, hit ratios of the cache after some uptime, and
how much RAM you have.
> Also the docs don't indicate if this memory is coming from the currently
> used memory pool, or if this is in excess of that. The one machine I am
> trying right now, is already using 128MB of swap so I am very
> concerned about memory.. Looking to see what I can move out of that
Again depends on schema - noteably what storage engine. Different storage
engines do different things. If you're swapping - especially if you're
using MyISAM, pull back on some buffer sizes. The query cache is a fixed
size, so if you set it to something, it won't grow. Other things will,
including the kernel's reliance on disk caches.
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