Re: Inconsistency in reporting checkpointer stats

On 2024/09/22 20:44, Nitin Jadhav wrote:
>> + CheckpointStats.ckpt_slru_written,
>> + (double) CheckpointStats.ckpt_slru_written * 100 / NBuffers,
>>
>> I don't think NBuffers represents the maximum number of SLRU buffers.
>> We might need to calculate this based on specific GUC settings,
>> like transaction_buffers.
>
> Great observation. Since the SLRU buffers written during a checkpoint
> can include transaction_buffers, commit_timestamp_buffers,
> subtransaction_buffers, multixact_member_buffers,
> multixact_offset_buffers, and serializable_buffers, the total count of
> SLRU buffers should be the sum of all these types. We might need to
> introduce a global variable, such as total_slru_count, in the
> globals.c file to hold this sum. The num_slots variable in the
> SlruSharedData structure needs to be accessed from all types of SLRU
> and stored in total_slru_count. This can then be used during logging
> to calculate the percentage of SLRU buffers written. However, I’m
> unsure if this effort is justified. While it makes sense for normal
> buffers to display the percentage, the additional code required might
> not provide significant value to users. Therefore, I have removed this
> in the attached v6 patch.

+1

Thanks for updating the patch! It looks good to me.
Barring any objections, I will commit this patch.

Regards,

--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION