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* [glibc/release/2.28/master] x86: Fix slight bug in `shared_per_thread` cache size calculation.
@ 2023-09-12 3:49 Noah Goldstein
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From: Noah Goldstein @ 2023-09-12 3:49 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=402324a71073ac36d334845a71a5f97350aebbc3
commit 402324a71073ac36d334845a71a5f97350aebbc3
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Fri Aug 11 18:48:18 2023 -0500
x86: Fix slight bug in `shared_per_thread` cache size calculation.
After:
```
commit af992e7abdc9049714da76cae1e5e18bc4838fb8
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Wed Jun 7 13:18:01 2023 -0500
x86: Increase `non_temporal_threshold` to roughly `sizeof_L3 / 4`
```
Split `shared` (cumulative cache size) from `shared_per_thread` (cache
size per socket), the `shared_per_thread` *can* be slightly off from
the previous calculation.
Previously we added `core` even if `threads_l2` was invalid, and only
used `threads_l2` to divide `core` if it was present. The changed
version only included `core` if `threads_l2` was valid.
This change restores the old behavior if `threads_l2` is invalid by
adding the entire value of `core`.
Reviewed-by: DJ Delorie <dj@redhat.com>
(cherry picked from commit 47f747217811db35854ea06741be3685e8bbd44d)
Diff:
---
sysdeps/x86/cacheinfo.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/sysdeps/x86/cacheinfo.c b/sysdeps/x86/cacheinfo.c
index 4354c01c71..6baec4d7ed 100644
--- a/sysdeps/x86/cacheinfo.c
+++ b/sysdeps/x86/cacheinfo.c
@@ -696,8 +696,8 @@ init_cacheinfo (void)
/* Account for non-inclusive L2 and L3 caches. */
if (!inclusive_cache)
{
- if (threads_l2 > 0)
- shared_per_thread += core / threads_l2;
+ long int core_per_thread = threads_l2 > 0 ? (core / threads_l2) : core;
+ shared_per_thread += core_per_thread;
shared += core;
}
}
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