| Date | Fri, 13 Jul 2018 18:14:06 -0400 | From | Johannes Weiner <> | Subject | Re: [PATCH 0/10] psi: pressure stall information for CPU, memory, and IO v2 |
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On Thu, Jul 12, 2018 at 04:44:22PM -0700, Andrew Morton wrote: > On Thu, 12 Jul 2018 13:29:32 -0400 Johannes Weiner <hannes@cmpxchg.org> wrote: > > > > > ... > > > > The io file is similar to memory. Because the block layer doesn't have > > a concept of hardware contention right now (how much longer is my IO > > request taking due to other tasks?), it reports CPU potential lost on > > all IO delays, not just the potential lost due to competition. > > Probably dumb question: disks aren't the only form of IO. Does it make > sense to accumulate PSI for other forms of IO? Networking comes to > mind...
It's conceivable, although I haven't thought too much about it yet. If that turns out to be a state we might want to track, we can easily add a task state to identify such stalls and add /proc/pressure/net e.g.
"io" in this case means only the block layer / filesystems. I think keeping this distinction makes sense in the interest of identifying which type of hardware resource is posing a pressure problem.
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