Re: Lock contention high

Hi,

On October 27, 2021 2:44:56 PM PDT, Ashkil Dighin <ashkildighin76(at)gmail(dot)com> wrote:
>Hi,
>Yes, lock contention reduced with postgresqlv14.
>Lock acquire reduced 18% to 10%
>10.49 %postgres postgres [.] LWLockAcquire
>5.09% postgres postgres [.] _bt_compare
>
>Is lock contention can be reduced to 0-3%?

Probably not, or at least not easily. Because of the atomic instructions the locking also includes some other costs (e.g. cache misses, serializing store buffers,...).

There's a good bit we can do to increase the cache efficiency around buffer headers, but it won't get us quite that low I'd guess.

>On pg-stat-activity shown LwLock as “BufferCounter” and “WalInsert”

Without knowing what proportion they have to each and to non-waiting backends that unfortunately doesn't help that much..

Andres

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