Peter Geoghegan writes:
> On 9 May 2012 00:21, Peter Geoghegan wrote:
>> Yes, there is some checking of flags before the potential ResetLatch()
>> call, which may be acted on. The code there is almost identical to
>> that of the extant bgwriter code. I was under the impression that this
>> did no
On further reflection I've realized that there's a really unpleasant
consequence of the walwriter change as-committed: it breaks the former
guarantee that async commits would reach disk within at most 3 times
the WalWriterDelay setting. They will still get written within at most
3 walwriter cycles
I've applied the walwriter/checkpointer patch, with the mentioned
re-simplification of the logic. While measuring that, I noticed that
the stats collector was now the biggest repeated-wakeup culprit, so
I took the time to latch-ify it as well. AFAICS we no longer have
anything that wakes up often
On 9 May 2012 00:21, Peter Geoghegan wrote:
> Yes, there is some checking of flags before the potential ResetLatch()
> call, which may be acted on. The code there is almost identical to
> that of the extant bgwriter code. I was under the impression that this
> did not amount to a race, though it's
Peter Geoghegan writes:
> On 8 May 2012 22:35, Tom Lane wrote:
>> Now that I've actually read the patch, rather than just responding to
>> your description of it, I find myself entirely unhappy with the proposed
>> changes in the walwriter's sleep logic. You have introduced race
>> conditions (i
On 8 May 2012 22:35, Tom Lane wrote:
> Now that I've actually read the patch, rather than just responding to
> your description of it, I find myself entirely unhappy with the proposed
> changes in the walwriter's sleep logic. You have introduced race
> conditions (it is NOT okay to reset the latc
Peter Geoghegan writes:
> Attached patch removes the questionable SetLatch() call, under the
> assumption that it's okay if the WALWriter, having entered hibernation
> due to sustained inactivity (10 seconds) subsequently takes up to 5
> seconds (2.5 on average) to notice that it has work to do. T
On 7 May 2012 20:06, Tom Lane wrote:
> Simon Riggs writes:
>> It also leaves the situation that we have a catalog view called
>> pg_stat_bgwriter that would be accessing "checkpointer" things. That's
>> really the thorny one that I wasn't sure how to handle. Good example
>> of why we shouldn't ex
Simon Riggs writes:
> It also leaves the situation that we have a catalog view called
> pg_stat_bgwriter that would be accessing "checkpointer" things. That's
> really the thorny one that I wasn't sure how to handle. Good example
> of why we shouldn't expose internals too much.
Yeah, that's a bit
On 7 May 2012 19:44, Tom Lane wrote:
> Simon Riggs writes:
>> On 7 May 2012 18:09, Tom Lane wrote:
>>> I also notice that the separate-checkpointer patch failed to rename
>>> assorted things like BgWriterCommLock, BgWriterRequest,
>>> BgWriterShmemStruct, which are all 100% inappropriately named
Simon Riggs writes:
> On 7 May 2012 18:09, Tom Lane wrote:
>> I also notice that the separate-checkpointer patch failed to rename
>> assorted things like BgWriterCommLock, BgWriterRequest,
>> BgWriterShmemStruct, which are all 100% inappropriately named now.
>> And it still contains various obsol
On 7 May 2012 18:09, Tom Lane wrote:
> Peter Geoghegan writes:
>> This latest revision also covers the checkpointer. The code for that
>> is far simpler than that for the WAL Writer, so it doesn't
>> particularly feel like I'm pushing my luck by slipping that into
>> something to be slipped in.
>
Peter Geoghegan writes:
> This latest revision also covers the checkpointer. The code for that
> is far simpler than that for the WAL Writer, so it doesn't
> particularly feel like I'm pushing my luck by slipping that into
> something to be slipped in.
Well ... maybe, or maybe not, or maybe you a
On 3 May 2012 10:56, Magnus Hagander wrote:
> I agree that it's ok to slip it in given that it's "finishing off a
> patch from earlier". I think it's reasonable to hold it to a little
> bit higher review stadards since it's that late in the cycle though,
> such as two people reviewing it before it
On Thu, May 3, 2012 at 2:41 AM, Robert Haas wrote:
> On Wed, May 2, 2012 at 7:21 PM, Tom Lane wrote:
>> It is getting a bit late to be considering such changes for 9.2, but
>> I'm willing to review and commit this if there's not anybody who feels
>> strongly that it's too late. Personally I thin
On 03.05.2012 03:41, Robert Haas wrote:
On Wed, May 2, 2012 at 7:21 PM, Tom Lane wrote:
Adding any contention at all to XLogInsert doesn't seem like a smart
idea, even if you failed to measure any problem in the specific tests
you made. I wonder whether we could not improve matters by adding
a
On Wed, May 2, 2012 at 11:42 PM, Tom Lane wrote:
> Robert Haas writes:
>> ... It seems unlikely to cause any real
>> problem if WAL writer takes a couple seconds to get with the program
>> after a long period of inactivity; note that an async commit will kick
>> it anyway, and a sync commit will
Robert Haas writes:
> ... It seems unlikely to cause any real
> problem if WAL writer takes a couple seconds to get with the program
> after a long period of inactivity; note that an async commit will kick
> it anyway, and a sync commit will probably half to flush WAL whether
> the WAL writer wake
On Wed, May 2, 2012 at 7:21 PM, Tom Lane wrote:
> It is getting a bit late to be considering such changes for 9.2, but
> I'm willing to review and commit this if there's not anybody who feels
> strongly that it's too late. Personally I think it's in the nature of
> cleanup and so fair game as lon
Peter Geoghegan writes:
> Attached patch latches up the WAL Writer, reducing wake-ups and thus
> saving electricity in a way that is more-or-less analogous to my work
> on the BGWriter:
> http://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=6d90eaaa89a007e0d365f49d6436f35d2392cfeb
> I am
Attached patch latches up the WAL Writer, reducing wake-ups and thus
saving electricity in a way that is more-or-less analogous to my work
on the BGWriter:
http://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=6d90eaaa89a007e0d365f49d6436f35d2392cfeb
I am hoping this gets into 9.2 . I am
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