On Nov 13, 2008, at 1:34 PM, Ivan Voras wrote:

Chris Pratt wrote:
I have asked this before a couple of years ago but received no
replies. I assumed that's because it's a somewhat obscure question.
I'm still interested and thought I might try again in case someone
new is watching this list who might know.

A vmstat -z on my highest traffic server always shows the failures
as below on 128 Bucket. It also goes to having 0 free rather soon
after the system is restarted and never returns to having more than
1 free in that column and yet always has the highest number of
requests by far. Does this mean anything significant? Is it
something I should tune or even can be tuned?

UMA buckets seem to be some kind of cache for SMP-optimized allocations
- I hope someone who knows it better will explain them.

Here is the output of the vmstat -z with everything chopped out
besides the 128 Bucket line. The machine it's on is an 8 core 8 GB
Tyan and shouldn't really be starved for anything in my way of thinking.

vmstat -z

128 Bucket: 1048, 0, 2043, 0, 13591, 6511069

What is the server used for?

A busy webserver (about 5G Views a month, average view is 3-4 hits). Not really large pages, we keep graphics minimal. It's apache, perl cgi, mysqld. Tends to collect a lot of garbage traffic attacks on top of real traffic, both TCP and UDP.

Here's a snapshot from a very loaded apache+php+pgsql web server, uptime
60 days (since the last power outage):

16 Bucket:                 76,        0,       42,       58,      125,
32 Bucket:                140,        0,       76,       64,      183,
64 Bucket:                268,        0,       74,       38,      438,
128 Bucket:               524,        0,     2060,      642,   788828,

A generic advice would be to increase vm.kmem_size (you're using AMD64,
right?) and see what happens.

I'll try that. I had heard this before in relation to KVA but have been concerned about trying it. If I can just change that knob and have an effect, seems worth
a try. If more than one person is doing it, it must be safe?

Yes, AMD64. Thank you very much.

freebsd-questions@freebsd.org mailing list
To unsubscribe, send any mail to "[EMAIL PROTECTED]"

Reply via email to