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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
Cc: Dmitry Dolgov <9erthalion6@gmail.com>
Cc: Michael Paquier <michael.paquier@gmail.com>
Cc: Vincent Lachenal <vincent.lachenal@gmail.com>
Cc: PostgreSQL mailing lists <pgsql-bugs@postgresql.org>
Subject: Re: BUG #14897: Segfault on statitics SQL request
Date: Sun, 12 Nov 2017 12:43:02 -0500
Message-ID: <3379.1510508582@sss.pgh.pa.us> (raw)
In-Reply-To: <9597.1510428707@sss.pgh.pa.us>
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I wrote:
> Andres Freund <andres@anarazel.de> writes:
>> Specifying MCXT_ALLOC_ALIGN_CACHELINE rather than CACHELINE_ALIGNMENT
>> doesn't seem to make it meaningfully harder to adjust. Or are you
>> thinking of probing the hardware?

> Yeah, the latter.  The two approaches seem pretty much equivalent if
> you're assuming compile-time decisions, but if we ever wanted a run-
> time decision, I think having a flag bit that's interpreted inside
> MemoryContextAllocExtended would be easier to deal with.

Actually, independently of which way we do that, it seems like we can't
easily hide this inside a palloc wrapper.  If we palloc some extra space
and then adjust the return value to be 16-aligned, what happens when the
caller tries to pfree the block?

			regards, tom lane


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  Subject: Re: BUG #14897: Segfault on statitics SQL request
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