Re: limiting hint bit I/O

On Thu, Jan 13, 2011 at 10:43 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> I whipped up the attached patch tonight.
>
> This appears to remove the BM_JUST_DIRTIED logic.  Please explain why
> that's not completely broken.  Even if it isn't completely broken,
> it would seem better to do something like that as a separate patch.

Well, the only point of BM_JUST_DIRTIED is to detect whether BM_DIRTY
has been set while a buffer write is in progress. With this patch,
only BM_HINT_BITS can be set while the buffer write is in progress;
BM_DIRTY cannot. Perhaps one could make the argument that this would
be a good cleanup anyway: in the unpatched code, BM_DIRTY can only be
set while a buffer I/O is in progress if it is set due to a hint-bit
update, and then we don't really care if the update gets lost.
Although that seems a bit confusing...

--
Robert Haas
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