Re: Abnormal values show up in /proc/allocinfo

[David Wang]

At 2024-11-27 01:10:23, "Suren Baghdasaryan" <surenb@xxxxxxxxxx> wrote:

>
>Hi David,
>Thanks for the investigation. I think your suggestion should work fine
>and it's simpler than what we do now. It will swap not only counters
>but allocation locations as well, however I think we already do that
>when we call __alloc_tag_ref_set(). So, instead of clearing the
>original tag, decrementing the new tag's counter (to compensate for
>its own allocation) and reassigning the old tag to the new counter,
>you simply swap the tags. That seems fine to me.
>However I think there is still a bug where some get_new_folio()
>callback does not increment the new folio's counters and that's why we
>get an underflow when calling alloc_tag_sub(). I'll try to reproduce
>on my side and see what's going on there.

Agreed, the reason for underflow with current code should be clarified.
Just update reproduce procedure:
1. fio --randrepeat=1 --ioengine=libaio --direct=1 --name=test  --bs=4k --iodepth=64 --size=1G --readwrite=randrw  --runtime=100 --numjobs=4 --time_based=1
2.  echo 1 >/proc/sys/vm/compact_memory
3.  echo 1 > /proc/sys/vm/drop_caches
(It is very strange, on my VM,  "echo 3 > /proc/sys/vm/drop_caches" would not trigger easily.  
4 cat /proc/allocinfo | grep __filemap_get_folio


FYI
David


>Thanks,
>Suren.
>
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>>  static void shutdown_mem_profiling(bool remove_file)
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>> FYI
>> David
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>> >
>> >Thanks~
>> >David
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>> >>
>> >>> > >Thanks,
>> >>> > >Suren.
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>> >>> > >>
>> >>> > >> Thanks
>> >>> > >> David
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