Re: Parallel Select query performance and shared buffers - Mailing list pgsql-hackers

From Claudio Freire
Subject Re: Parallel Select query performance and shared buffers
Date
Msg-id CAGTBQpbRNt7oK9Z9dJpN_ChV4TqBZpYD+634Zm1wg4NjC_Zx2w@mail.gmail.com
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In response to Re: Parallel Select query performance and shared buffers  (Metin Doslu <metin@citusdata.com>)
Responses Re: Parallel Select query performance and shared buffers  (Andres Freund <andres@2ndquadrant.com>)
Re: Parallel Select query performance and shared buffers  (Metin Doslu <metin@citusdata.com>)
List pgsql-hackers
On Wed, Dec 4, 2013 at 9:19 AM, Metin Doslu <metin@citusdata.com> wrote:
>
> Here are the results of "vmstat 1" while running 8 parallel TPC-H Simple
> (#6) queries:  Although there is no need for I/O, "wa" fluctuates between 0
> and 1.
>
> procs -----------memory---------- ---swap-- -----io---- --system--
> -----cpu-----
>  r  b   swpd   free   buff    cache     si   so    bi    bo    in     cs us sy  id wa st
>  0  0      0 30093568  84892 38723896    0    0     0     0    22     14  0  0 100  0  0
>  8  1      0 30043056  84892 38723896    0    0     0     0 27080  52708 16 14  70  0  0
>  8  1      0 30006600  84892 38723896    0    0     0     0 44952 118286 43 44  12  1  0
>  8  0      0 29986264  84900 38723896    0    0     0    20 28043  95934 49 42   8  1  0
>  7  0      0 29991976  84900 38723896    0    0     0     0  8308  73641 52 42   6  0  0
>  0  0      0 30091828  84900 38723896    0    0     0     0  3996  30978 23 24  53  0  0
>  0  0      0 30091968  84900 38723896    0    0     0     0    17    23   0  0 100  0  0


Notice the huge %sy

What kind of VM are you using? HVM or paravirtual?


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