| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | James Bottomley <James(dot)Bottomley(at)hansenpartnership(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andres Freund <andres(at)2ndquadrant(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, Hannu Krosing <hannu(at)2ndquadrant(dot)com>, "lsf-pc(at)lists(dot)linux-foundation(dot)org" <lsf-pc(at)lists(dot)linux-foundation(dot)org>, 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>, Trond Myklebust <trondmy(at)gmail(dot)com>, Magnus Hagander <magnus(at)hagander(dot)net> |
| Subject: | Re: [Lsf-pc] Linux kernel impact on PostgreSQL performance |
| Date: | 2014-01-14 16:48:32 |
| Message-ID: | CA+Tgmoa5Jt4k6mqTYbiJP5Ot1HTpVKWs=s_-aVvZk9BGooFq9Q@mail.gmail.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On Tue, Jan 14, 2014 at 11:44 AM, James Bottomley
<James(dot)Bottomley(at)hansenpartnership(dot)com> wrote:
> No, I'm sorry, that's never going to be possible. No user space
> application has all the facts. If we give you an interface to force
> unconditional holding of dirty pages in core you'll livelock the system
> eventually because you made a wrong decision to hold too many dirty
> pages. I don't understand why this has to be absolute: if you advise
> us to hold the pages dirty and we do up until it becomes a choice to
> hold on to the pages or to thrash the system into a livelock, why would
> you ever choose the latter? And if, as I'm assuming, you never would,
> why don't you want the kernel to make that choice for you?
If you don't understand how write-ahead logging works, this
conversation is going nowhere. Suffice it to say that the word
"ahead" is not optional.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Claudio Freire | 2014-01-14 16:49:51 | Re: [Lsf-pc] Linux kernel impact on PostgreSQL performance |
| Previous Message | James Bottomley | 2014-01-14 16:44:16 | Re: [Lsf-pc] Linux kernel impact on PostgreSQL performance |