| From: | Hannu Krosing <hannu(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com>, James Bottomley <James(dot)Bottomley(at)hansenpartnership(dot)com> |
| Cc: | Andres Freund <andres(at)2ndquadrant(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, Trond Myklebust <trondmy(at)gmail(dot)com>, Kevin Grittner <kgrittn(at)ymail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>, Dave Chinner <david(at)fromorbit(dot)com>, Joshua Drake <jd(at)commandprompt(dot)com>, Claudio Freire <klaussfreire(at)gmail(dot)com>, Mel Gorman <mgorman(at)suse(dot)de>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "lsf-pc(at)lists(dot)linux-foundation(dot)org" <lsf-pc(at)lists(dot)linux-foundation(dot)org>, Magnus Hagander <magnus(at)hagander(dot)net> |
| Subject: | Re: [Lsf-pc] Linux kernel impact on PostgreSQL performance |
| Date: | 2014-01-15 11:16:50 |
| Message-ID: | 52D66E22.9070207@2ndQuadrant.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On 01/14/2014 06:12 PM, Robert Haas wrote:
> This would be pretty similar to copy-on-write, except
> without the copying. It would just be
> forget-from-the-buffer-pool-on-write.
+1
A version of this could probably already be implement using MADV_DONTNEED
and MADV_WILLNEED
Thet is, just after reading the page in, use MADV_DONTNEED on it. When
evicting
a clean page, check that it is still in cache and if it is, then
MADV_WILLNEED it.
Another nice thing to do would be dynamically adjusting kernel
dirty_background_ratio
and other related knobs in real time based on how many buffers are dirty
inside postgresql.
Maybe in background writer.
Question to LKM folks - will kernel react well to frequent changes to
/proc/sys/vm/dirty_* ?
How frequent can they be (every few second? every second? 100Hz ?)
Cheers
--
Hannu Krosing
PostgreSQL Consultant
Performance, Scalability and High Availability
2ndQuadrant Nordic OÜ
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Hannu Krosing | 2014-01-15 11:23:45 | Re: [Lsf-pc] Linux kernel impact on PostgreSQL performance |
| Previous Message | Mel Gorman | 2014-01-15 11:05:25 | Re: [Lsf-pc] Linux kernel impact on PostgreSQL performance |