| From: | Amit Langote <amitlangote09(at)gmail(dot)com> |
|---|---|
| To: | Bruce Momjian <bruce(at)momjian(dot)us> |
| Cc: | Simon Riggs <simon(at)2ndquadrant(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Magnus Hagander <magnus(at)hagander(dot)net>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Claudio Freire <klaussfreire(at)gmail(dot)com>, Merlin Moncure <mmoncure(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: proposal: Set effective_cache_size to greater of .conf value, shared_buffers |
| Date: | 2014-05-15 14:36:51 |
| Message-ID: | CA+HiwqH=Nd_J2rM5n0_9QuCBNnpSVxf04bz+34qxSK3NC6hbmw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, May 15, 2014 at 11:24 PM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> On Thu, May 15, 2014 at 10:23:19PM +0900, Amit Langote wrote:
>> On Thu, May 15, 2014 at 9:06 PM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
>> >
>> > This is the same problem we had with auto-tuning work_mem, in that we
>> > didn't know what other concurrent activity was happening. Seems we need
>> > concurrent activity detection before auto-tuning work_mem and
>> > effective_cache_size.
>> >
>>
>> Perhaps I am missing something obvious here, but would mmgr have any
>> useful numbers on this? Like any book-keeping info maintained by
>> mcxt.c/aset.c? Would extending that interface help?
>
> No, all memory allocat is per-process, except for shared memory. We
> probably need a way to record our large local memory allocations in
> PGPROC that other backends can see; same for effective cache size
> assumptions we make.
>
I see. I thought there would be some centralised way to traverse, say,
a linked list of contexts that individual backends create or something
like that. But, I suppose it would not be straightforward to make any
of that work for what we are after here.
--
Amit
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