| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Tomas Vondra <tv(at)fuzzy(dot)cz>, Simon Riggs <simon(at)2ndquadrant(dot)com>, pgsql-committers <pgsql-committers(at)postgresql(dot)org>, Andrew Dunstan <andrew(at)dunslane(dot)net> |
| Subject: | Re: pgsql: Generational memory allocator |
| Date: | 2017-11-23 22:04:36 |
| Message-ID: | 13547.1511474676@sss.pgh.pa.us |
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| Lists: | pgsql-committers |
Andres Freund <andres(at)anarazel(dot)de> writes:
> On 2017-11-23 22:34:57 +0100, Tomas Vondra wrote:
>> Hmmm, I see. Presumably adding this to GenerationChunk (similarly to what we
>> do in AllocChunkData) would address the issue:
>>
>> #if MAXIMUM_ALIGNOF > 4 && SIZEOF_VOID_P == 4
>> Size padding;
>> #endif
>>
>> but I have no way to verify that (no access to such machine). I wonder why
>> SlabChunk doesn't need to do that (perhaps a comment explaining that would
>> be appropriate?).
> Can't you just compile pg on a 32bit system and manually define MAXALIGN
> to 8 bytes?
I pushed a patch that computes how much padding to add and adds it.
(It might not really work if size_t and void * are different sizes,
because then there could be additional padding in the struct; but
that seems very unlikely.)
regards, tom lane
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