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Startup speed #665

Merged
merged 3 commits into from
Jun 26, 2024
Merged

Startup speed #665

merged 3 commits into from
Jun 26, 2024

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mjp41
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@mjp41 mjp41 commented Jun 18, 2024 •
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This improves the startup time for a heavily multi-threaded workload.

There are two improvements that are independent of each other:

  1. Buddy allocator has local cache. The buddy allocator uses the pagemap as backing store. This means that a lot of pages are faulted in at startup for the pagemap, when a large unaligned block is added. This was causing a noticeable time in micro-profiling. The change in this PR makes there be a few entries at the top-level, so we only use the pagemap once a reasonable amount entries are required.
  2. DODUMP/DONTDUMP on Linux were costing a noticeable amount of time, and causing a significant slow down. This PR also exposes a new couple of optional operations on the PAL, and only applies these operations to the Pagemap.

@mjp41
Refactor buddy allocator
65de041 
Make it clearer the structure of add_block by pulling out remove_buddy.
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mjp41 commented Jun 19, 2024

After private feedback from @vishalgupta97 and @nwf-msr I am going to put the lock in a separate PR.

@mjp41
Give buddy a few elements so don't have to touch pagemap earlie on.
aec908f
@mjp41
Only use do and dont dump on pagemap
e3b6929 
The do and dont dump calls were costings a lot during start up of snmalloc.  This reduces the times they are called to only be for the pagemap.
@mjp41 mjp41 marked this pull request as ready for review June 19, 2024 18:42
nwf-msr
nwf-msr approved these changes Jun 26, 2024
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LGTM

@mjp41 mjp41 merged commit 4620220 into microsoft:main Jun 26, 2024
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@mjp41 mjp41 deleted the startup_speed branch June 26, 2024 20:34
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@nwf-msr nwf-msr nwf-msr approved these changes

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