Обсуждение: Re: Improve CRC32C performance on SSE4.2

Hi,

Recently I always get below error during initdb.

"""
UTC [1358059] FATAL:  incorrect checksum in control file
"""

the command is "initdb -D tmp". git bisect show me the related commit is 
3c6e8c123896584f1be1fe69aaf68dcb5eb094d5. After revert this commit on
the current master, everything is fine.  Does anyone knows the reason?

The attached is my config.log.


-- 
Best Regards
Andy Fan

Hi,

I suggest you try with a newer gcc, perhaps 13.4. There's been a bunch
of fixes related to AVX512 since 13.0, chances are this was already
fixed. I don't see this failure on 14.3.1.

T.

On 6/14/25 12:24, Andy Fan wrote:
> Hi,
> 
> Recently I always get below error during initdb.
> 
> """
> UTC [1358059] FATAL:  incorrect checksum in control file
> """
> 
> the command is "initdb -D tmp". git bisect show me the related commit is 
> 3c6e8c123896584f1be1fe69aaf68dcb5eb094d5. After revert this commit on
> the current master, everything is fine.  Does anyone knows the reason?
> 
> The attached is my config.log.
> 
> 
> 

-- 
Tomas Vondra

On Sat, Jun 14, 2025 at 03:47:33PM +0200, Tomas Vondra wrote:
> I suggest you try with a newer gcc, perhaps 13.4. There's been a bunch
> of fixes related to AVX512 since 13.0, chances are this was already
> fixed. I don't see this failure on 14.3.1.

From the config.log, it looks like Andy is using clang:

    configure:3998: clang --version >&5
    clang version 18.1.6 (https://gitee.com/mirrors/llvm-project.git 1118c2e05e67a36ed8ca250524525cdb66a55256)

And I see -O0 used, too, which would match the existing report [0],
although that report is for clang 19.1.7.

I'm also genuinely curious why folks are using -O0...

[0] https://postgr.es/m/CAE-ML%2B-OV6p9uvCFBcSQjZUEh__y0h-KjN%2BBseyGJHt7u8EP%2Bw%40mail.gmail.com

-- 
nathan

On 6/14/25 15:56, Nathan Bossart wrote:
> On Sat, Jun 14, 2025 at 03:47:33PM +0200, Tomas Vondra wrote:
>> I suggest you try with a newer gcc, perhaps 13.4. There's been a bunch
>> of fixes related to AVX512 since 13.0, chances are this was already
>> fixed. I don't see this failure on 14.3.1.
> 
> From the config.log, it looks like Andy is using clang:
> 
>     configure:3998: clang --version >&5
>     clang version 18.1.6 (https://gitee.com/mirrors/llvm-project.git 1118c2e05e67a36ed8ca250524525cdb66a55256)
> 
> And I see -O0 used, too, which would match the existing report [0],
> although that report is for clang 19.1.7.
> 

Ah, I got confused by this:

-----------------
Found candidate GCC installation:
/usr/local/bin/../lib/gcc/x86_64-pc-linux-gnu/13.3.0
Selected GCC installation:
/usr/local/bin/../lib/gcc/x86_64-pc-linux-gnu/13.3.0
-----------------

> I'm also genuinely curious why folks are using -O0...
> 
> [0] https://postgr.es/m/CAE-ML%2B-OV6p9uvCFBcSQjZUEh__y0h-KjN%2BBseyGJHt7u8EP%2Bw%40mail.gmail.com
> 

I personally use -O0 to get better backtraces (without values optimized
out), better valgrind reports, etc.


-- 
Tomas Vondra

Hi Nathan,

On 6/14/25 9:56 AM, Nathan Bossart wrote:
> I'm also genuinely curious why folks are using -O0...
> 

Personally, I use

  -O0 -fno-omit-frame-pointer

for FlameGraph [1] investigations.

[1] https://github.com/brendangregg/FlameGraph

Best regards,
  Jesper