| From: | Andrey Borodin <x4mmm(at)yandex-team(dot)ru> |
|---|---|
| To: | Thomas Munro <thomas(dot)munro(at)gmail(dot)com> |
| Cc: | Gilles Darold <gilles(at)darold(dot)net>, Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Alexander Korotkov <aekorotkov(at)gmail(dot)com>, Anastasia Lubennikova <a(dot)lubennikova(at)postgrespro(dot)ru>, Daniel Gustafsson <daniel(at)yesql(dot)se>, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: MultiXact\SLRU buffers configuration |
| Date: | 2021-03-26 15:52:22 |
| Message-ID: | 75B95FDD-2BE0-4525-8BDD-FC67C8BCBD53@yandex-team.ru |
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| Lists: | pgsql-hackers |
> 26 марта 2021 г., в 11:00, Andrey Borodin <x4mmm(at)yandex-team(dot)ru> написал(а):
>
>> I'm not saying the 0002 patch is bug-free yet though, it's a bit finickity.
> I think the idea of speeding up linear search is really really good for scaling SLRUs. It's not even about improving normal performance of the cluster, but it's important from preventing pathological degradation under certain circumstances. Bigger cache really saves SLAs :) I'll look into the patch more closely this weekend. Thank you!
Some thoughts on HashTable patch:
1. Can we allocate bigger hashtable to reduce probability of collisions?
2. Can we use specialised hashtable for this case? I'm afraid hash_search() does comparable number of CPU cycles as simple cycle from 0 to 128. We could inline everything and avoid hashp->hash(keyPtr, hashp->keysize) call. I'm not insisting on special hash though, just an idea.
3. pageno in SlruMappingTableEntry seems to be unused.
Thanks!
Best regards, Andrey Borodin.
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