Re: [HACKERS] PATCH: two slab-like memory allocators

On 02/27/2017 05:48 PM, Andres Freund wrote:
> On 2017-02-27 07:55:32 -0800, Andres Freund wrote:
>> On 2017-02-27 10:32:25 -0500, Tom Lane wrote:
>>> Andres Freund <andres@anarazel.de> writes:
>>>> And pushed slab and its usage.  Will have a look at generation.c
>>>> tomorrow.
>>>
>>> Perhaps first you need to find out why so much of the buildfarm
>>> is unhappy.
>>
>> Will do, after a morning coffee.
>
> Hm. Not entirely clear on what's going on yet. I've run the tests on
> hydra (community ppc 64 machine), which is pretty similar to termite
> which failed [1] with:
> TRAP: BadArgument("!(((context) != ((void *)0) && (((((const Node*)((context)))->type) == T_AllocSetContext) ||
((((constNode*)((context)))->type) == T_SlabContext))))", File:
"/home/pgbuildfarm/buildroot-termite/HEAD/pgsql.build/../pgsql/src/backend/utils/mmgr/mcxt.c",Line: 1010)
 
>
> The best theory I have so far that I have is that slab.c's idea of
> StandardChunkHeader's size doesn't match what mcxt.c think it is
> (because slab.c simply embeds StandardChunkHeader, but mcxt uses
> MAXALIGN(sizeof(StandardChunkHeader))).  That's not good, but I don't
> quite see how that'd cause the issue, since StandardChunkHeader's size
> should always be properly sized.
>
> Tomas, do you have access to termite (which appears to be run by Craig,
> under company mail).
>

No, I don't, but I'll ping Craig. I might ping him, but it's ~4AM in 
Australia, though, so it'll take time.

FWIW I think the ppc64 machines are failing because of unrelated issue 
(changes to integer timestamps). We should probably look at 32bit 
machines first.

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
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