| From: | David Rees <drees76(at)gmail(dot)com> |
|---|---|
| To: | Craig James <craig_james(at)emolecules(dot)com> |
| Cc: | jd(at)commandprompt(dot)com, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Occasional giant spikes in CPU load |
| Date: | 2010-04-07 23:52:47 |
| Message-ID: | z2v72dbd3151004071652oce71dc69n6dea759617e4be@mail.gmail.com |
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| Lists: | pgsql-performance |
On Wed, Apr 7, 2010 at 3:57 PM, Craig James <craig_james(at)emolecules(dot)com> wrote:
> On 4/7/10 3:36 PM, Joshua D. Drake wrote:
>> My guess is that it is not CPU, it is IO and your CPU usage is all WAIT
>> on IO.
>>
>> To have your CPUs so flooded that they are the cause of an inability to
>> log in is pretty suspect.
>
> I thought so too, except that I can't login during the flood. If the CPUs
> were all doing iowaits, logging in should be easy.
No - logging in with high iowait is very harder to do than high CPU
time because of latency of disk access.
> Greg's suggestion that shared_buffers and work_mem are too big for an 8 GB
> system fits these symptoms -- if it's having a swap storm, login is
> effectively impossible.
A swap storm effectively puts the machine into very high iowait time.
-Dave
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