lkml.org 
[lkml]   [2021]   [Dec]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH] mm: count zram read/write into PSI_IO_WAIT
Zhaoyang Huang writes:
>No. Block device related D-state will be counted in via
>psi_dequeue(io_wait). What I am proposing here is do NOT ignore the
>influence on non-productive time by huge numbers of in-context swap
>in/out (zram like). This can help to make IO pressure more accurate
>and coordinate with the number of PSWPIN/OUT. It is like counting the
>IO time within filemap_fault->wait_on_page_bit_common into
>psi_mem_stall, which introduces memory pressure high by IO.

I think part of the confusion here is that the name "io" doesn't really just
mean "io", it means "disk I/O". As in, we are targeting real, physical or
network disk I/O. Of course, we can only do what's reasonable if the device
we're accounting for is layers upon layers eventually leading to a
memory-backed device, but _intentionally_ polluting that with more memory-bound
accesses doesn't make any sense when we already have separate accounting for
memory. Why would anyone want that?

I'm with Johannes here, I think this would actively make memory pressure
monitoring less useful. This is a NAK from my perspective as someone who
actually uses these things in production.

\
 
 \ /
  Last update: 2021-12-08 18:46    [W:0.079 / U:0.264 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site