Le 01/07/2023 à 00:09, Thomas Munro a écrit :
On Fri, Jun 30, 2023 at 10:47 PM Palak Chaturvedi
<chaturvedipalak1...@gmail.com> wrote:
We also talked a bit about how one might control the kernel page cache
in more fine-grained ways for testing purposes, but it seems like the
pgfincore project has that covered with its pgfadvise_willneed() and
pgfadvise_dontneed(). IMHO that project could use more page-oriented
operations (instead of just counts and coarse grains operations) but
that's something that could be material for patches to send to the
extension maintainers. This work, in contrast, is more tangled up
with bufmgr.c internals, so it feels like this feature belongs in a
core contrib module.
Precisely what pgfincore is doing/offering already.
Happy to propose to postgresql tree if there are interest. Next step for
pgfincore is to add cachestat() syscall and evaluates benefits for
PostgreSQL cost estimators of this new call.
Here an example to achieve the warm/unwarm, each bit is a PostgreSQL
page, so here we warm cache with the first 3 and remove the last 3 from
cache (system cache, not shared buffers).
-- Loading and Unloading
cedric=# select * from pgfadvise_loader('pgbench_accounts', 0, true,
true, B'111000');
relpath | os_page_size | os_pages_free | pages_loaded |
pages_unloaded
------------------+--------------+---------------+--------------+----------------
base/11874/16447 | 4096 | 408376 | 3 |
3
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Cédric Villemain +33 (0)6 20 30 22 52
https://Data-Bene.io
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