| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | "Jignesh K(dot) Shah" <J(dot)K(dot)Shah(at)sun(dot)com> |
| Cc: | Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Scott Carey <scott(at)richrelevance(dot)com>, Greg Smith <gsmith(at)gregsmith(dot)com>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Proposal of tunable fix for scalability of 8.4 |
| Date: | 2009-03-21 00:45:28 |
| Message-ID: | 603c8f070903201745m575642f5s539e1a374ce4ce9f@mail.gmail.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
On Fri, Mar 20, 2009 at 7:39 PM, Jignesh K. Shah <J(dot)K(dot)Shah(at)sun(dot)com> wrote:
> Alvaro Herrera wrote:
>>> So Simon's correct.
>> And perhaps this explains why Jignesh is measuring an improvement on his
>> benchmark. Perhaps an useful experiment would be to turn this behavior
>> off and compare performance. This lack of measurement is probably the
>> cause that the suggested patch to fix it was never applied.
>>
>> The patch is here
>> http://archives.postgresql.org//pgsql-hackers/2004-11/msg00935.php
>
> One of the reasons why my patch helps is it keeps this check intact but
> allows other exclusive Wake up.. Now what PostgreSQL calls "Wakes" is in
> reality just makes a variable indicating wake up and not really signalling a
> process to wake up. This is a key point to note. So when the process wanting
> the exclusive fights the OS Scheduling policy to finally get time on the CPU
> then it check the value to see if it is allowed to wake up and potentially
I'm confused. Is a process waiting for an LWLock is in a runnable
state? I thought we went to sleep on a semaphore.
...Robert
| From | Date | Subject | |
|---|---|---|---|
| Next Message | M. Edward (Ed) Borasky | 2009-03-21 04:17:05 | "iowait" bug? |
| Previous Message | Robert Haas | 2009-03-21 00:37:52 | Re: Need help with one query |