Re: Reducing the chunk header sizes on all memory context types

From: David Rowley <dgrowleyml(at)gmail(dot)com>
To: Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Robert Haas <robertmhaas(at)gmail(dot)com>, Yura Sokolov <y(dot)sokolov(at)postgrespro(dot)ru>, PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Reducing the chunk header sizes on all memory context types
Date: 2022-08-30 00:45:07
Message-ID: CAApHDvrk=v8XR4+WHSoNAomh1_t93OHdc9LTUsYpMYv1=th2Xw@mail.gmail.com
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

On Tue, 30 Aug 2022 at 03:39, Tomas Vondra
<tomas(dot)vondra(at)enterprisedb(dot)com> wrote:
> The attached patch seems to fix the issue for me - at least it seems
> like that. This probably will need to get backpatched, I guess. Maybe we
> should add an assert to MemoryChunkGetPointer to check alignment?

Hi Tomas,

I just wanted to check with you if you ran the full make check-world
with this patch?

I don't yet have a working ARM 32-bit environment to test, but on
trying it with x86 32-bit and adjusting MAXIMUM_ALIGNOF to 8, I'm
getting failures in test_decoding. Namely:

test twophase ... FAILED 51 ms
test twophase_stream ... FAILED 25 ms

INSERT INTO test_prepared2 VALUES (5);
SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL,
NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
+WARNING: problem in slab Change: detected write past chunk end in
block 0x58b8ecf0, chunk 0x58b8ed08
+WARNING: problem in slab Change: detected write past chunk end in
block 0x58b8ecf0, chunk 0x58b8ed58
+WARNING: problem in slab Change: detected write past chunk end in
block 0x58b8ecf0, chunk 0x58b8eda8
+WARNING: problem in slab Change: detected write past chunk end in
block 0x58b8ecf0, chunk 0x58b8edf8
+WARNING: problem in slab Change: detected write past chunk end in
block 0x58b8ecf0, chunk 0x58b8ee48

I think the existing sentinel check looks wrong:

if (!sentinel_ok(chunk, slab->chunkSize))

shouldn't that be passing the pointer rather than the chunk?

David

In response to

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Michael Paquier 2022-08-30 00:57:10 Re: Bump MIN_WINNT to 0x0600 (Vista) as minimal runtime in 16~
Previous Message Andres Freund 2022-08-30 00:33:56 Re: [PATCH] Add native windows on arm64 support