From: David Rees <drees76@gmail.com>
To: Craig James <craig_james@emolecules.com>
Cc: jd@commandprompt.com
Cc: pgsql-performance@postgresql.org
Subject: Re: Occasional giant spikes in CPU load
Date: Wed, 7 Apr 2010 16:52:47 -0700
Message-ID: <z2v72dbd3151004071652oce71dc69n6dea759617e4be@mail.gmail.com> (raw)
In-Reply-To: <4BBD0DD5.3050807@emolecules.com>
References: <k2pda0294261004061437p9cd3810dqe9ce528b6ddb0873@mail.gmail.com>
<m2m603c8f071004071413w1f2d2497hbbe07d9c6491848f@mail.gmail.com>
<4BBCFB12.1010306@emolecules.com>
<1270676410.19131.21.camel@jd-desktop.unknown.charter.com>
<4BBCFCDE.5020405@emolecules.com>
<1270679808.19131.28.camel@jd-desktop.unknown.charter.com>
<4BBD0DD5.3050807@emolecules.com>
On Wed, Apr 7, 2010 at 3:57 PM, Craig James <craig_james@emolecules.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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To: pgsql-performance@postgresql.org
Cc: drees76@gmail.com, craig_james@emolecules.com, jd@commandprompt.com
Subject: Re: Occasional giant spikes in CPU load
In-Reply-To: <z2v72dbd3151004071652oce71dc69n6dea759617e4be@mail.gmail.com>
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