Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Number of stripes is non-configurable #13

Closed
parsonsmatt opened this issue Nov 9, 2022 · 5 comments · Fixed by #17 · May be fixed by #16
Closed

Number of stripes is non-configurable #13

parsonsmatt opened this issue Nov 9, 2022 · 5 comments · Fixed by #17 · May be fixed by #16

Comments

@parsonsmatt
Copy link

Version 2 would accept an Int parameter for how many stripes to create. Version 3 uses getNumCapabilites unconditionally.

We're running into problems upgrading, and I think this may be related. Previously, with a createPool _ _ 1 3600 4 call, you'd have 1 stripe and 4 resources per stripe. But now you will have 4 stripes, with 1 resource per stripe. Locally, I'm seeing errors about "refusing to create resource 12", when we have a createPool _ _ 1 3600 4 call.

getNumCapabilities on my machine returns 20, so when we calculate the max resources, we get 4 (4 resources, 1 stripe). Then we get 20 stripes, each with 1 resource each.

I'd suggest adding a field for configuring stripe count on PoolConfig - that should alleviate this issue.
@parsonsmatt
Copy link
Author

IMO it seems pretty dodgy that poolMaxResources is actually a lower bound on how many resources can be created, and that it can create potentially many more.

I'm going to submit a patch that accepts a poolNumStripes config parameter. The smallest change is to use that instead of getNumCapabilities when it is present. A more invasive change is to ensure that only enough Stripes are created such that poolMaxResources is never exceeded (ie requesting poolMaxResources = 4 and poolNumStripes = 5 only actually creates 4 stripes, so that we definitely do not exceed the poolMaxResources).

This was referenced Nov 9, 2022
Closed
Open
@ruicc ruicc mentioned this issue Dec 5, 2022
Merged
@arybczak arybczak mentioned this issue Dec 14, 2022
Merged
@arybczak
Copy link
Contributor

Then we get 20 stripes, each with 1 resource each.

Out of curiosity, why are you running 20 capabilities? Do you have a machine with 20 physical cores?

@parsonsmatt
Copy link
Author

Yes, my laptop has 20 cores. getNumCapabilities >>= print shows 20.

@arybczak
Copy link
Contributor

I see. How many of these are physical? Asking since according to my experimentations running more capabilities than physical cores (and if you run with +RTS -N, getNumCapabilities will give you the number of logical cores) reduces performance, most likely due to GC overhead (and perhaps redundant context switches).

@parsonsmatt
Copy link
Author

Huh apparently I have 14 physical cores, 8 "effiicency" and 6 "performance." Wild! And I guess hyperthreading gets me up to 20.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Assignees
No one assigned
Labels
None yet
Projects
None yet
Milestone
No milestone
2 participants
@arybczak @parsonsmatt