| From: | Claudio Freire <klaussfreire(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)2ndquadrant(dot)com> |
| Cc: | Metin Doslu <metin(at)citusdata(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, postgres performance list <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Parallel Select query performance and shared buffers |
| Date: | 2013-12-04 18:00:40 |
| Message-ID: | CAGTBQpb5_K-_YY96D-CRh=mKq6AQW45ztptV5akCNUuV7jxR_A@mail.gmail.com |
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| Lists: | pgsql-hackers pgsql-performance |
On Wed, Dec 4, 2013 at 1:54 PM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
> On 2013-12-04 18:43:35 +0200, Metin Doslu wrote:
>> > I'd strongly suggest doing a "perf record -g -a <wait a bit, ctrl-c>;
>> > perf report" run to check what's eating up the time.
>>
>> Here is one example:
>>
>> + 38.87% swapper [kernel.kallsyms] [k] hypercall_page
>> + 9.32% postgres [kernel.kallsyms] [k] hypercall_page
>> + 6.80% postgres [kernel.kallsyms] [k] xen_set_pte_at
>
> All that time is spent in your virtualization solution. One thing to try
> is to look on the host system, sometimes profiles there can be more
> meaningful.
You cannot profile the host on EC2.
You could try HVM. I've noticed it fare better under heavy CPU load,
and it's not fully-HVM (it still uses paravirtualized network and
I/O).
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