vminitd: Lower nio event loop group threads to 1#677
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dcantah wants to merge 1 commit intoapple:mainfrom
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vminitd: Lower nio event loop group threads to 1#677dcantah wants to merge 1 commit intoapple:mainfrom
dcantah wants to merge 1 commit intoapple:mainfrom
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The event loop group threads afaict are for ingesting the requests,
and then they're fanned out to the Swift concurrency threads. vminitd
is at it's heart not very request heavy. It typically does sequential
rpcs until the container is up and running, and then all IO happens
on vsock ports out of band of grpc entirely. We do not need {core count
of guest} threads servicing requests as far as I can see. The real killer
is that each thread seems to consume 3MiB of RSS, which causes the overhead
of RAM we give to the guest to account for vminitd to be out of whack. It also
caused vminitds memory usage to scale with the core count of the guest, which
is similarly insane.
This change:
- Uses 1 thread to service the grpc server
- Moves the blocking thread pool which today is used for copy operations down
to 2. This does mean you can only do 2 copy operations in parallel, but this
does not worry me.
- Bumps vminitds overhead to 75. Now, at idle vminitd hovers around 45-50MiB,
which still feels a tad high, but much better after {-3*coreCount}MiB which would
cause 8 core guests to be in the 70s. Keep our cgroup high memory accounting
for vminitd at 75MiB, so now it matches the actual overhead RAM we give.
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The event loop group threads afaict are for ingesting the requests, and then they're fanned out to the Swift concurrency threads. vminitd is at it's heart not very request heavy. It typically does sequential rpcs until the container is up and running, and then all IO happens on vsock ports out of band of grpc entirely. We do not need {core count of guest} threads servicing requests as far as I can see. The real killer is that each thread in the elg seems to consume 3MiB of RSS, which causes the overhead of RAM we give to the guest to account for vminitd to be out of whack. It also caused vminitds memory usage to scale with the core count of the guest, which is similarly insane.
This change: