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From: "Tang, Jun" <juntangc@amazon.com>
To: "libc-alpha@sourceware.org" <libc-alpha@sourceware.org>
Cc: "Pop, Sebastian" <spop@amazon.com>
Subject: bug fix for hp-timing.h (aarch64)
Date: Wed, 11 Jan 2023 16:44:30 +0000	[thread overview]
Message-ID: <8ae95272accb441aad774a5f10d27d57@amazon.com> (raw)

[-- Attachment #1: Type: text/plain, Size: 909 bytes --]

On Graviton 3 the frequency is 1050000000 and the original function hp-timing.h no longer gives the correct answer. The following patch can fix the bug:

```
diff --git a/sysdeps/aarch64/hp-timing.h b/sysdeps/aarch64/hp-timing.h
index c8469e3011..c5a1204d2c 100644
--- a/sysdeps/aarch64/hp-timing.h
+++ b/sysdeps/aarch64/hp-timing.h
@@ -41,7 +41,7 @@ typedef uint64_t hp_timing_t;
#define HP_TIMING_DIFF(Diff, Start, End)                       \
({  hp_timing_t freq;                                          \
     __asm__ __volatile__ ("mrs %0, cntfrq_el0" : "=r" (freq)); \
-   (Diff) = ((End) - (Start)) * (UINT64_C(1000000000) / freq); \
+   (Diff) = (hp_timing_t)((End) - (Start)) * ((1000000000.0) / freq);  \
})
 #endif /* hp-timing.h */
```

I have also submitted a bug report with the proposed changes at -
https://sourceware.org/bugzilla/show_bug.cgi?id=29329

Regards,

Jun

             reply	other threads:[~2023-01-11 16:48 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-11 16:44 Tang, Jun [this message]
2023-01-11 17:22 ` Zack Weinberg
2023-01-31 14:47   ` Tang, Jun
2023-01-11 22:49 Wilco Dijkstra
2023-01-12 14:38 ` Tang, Jun
2023-01-12 18:07   ` Wilco Dijkstra
2023-01-12 18:54     ` Zack Weinberg
2023-01-12 20:32       ` Wilco Dijkstra
2023-01-12 20:51         ` Noah Goldstein
2023-01-16 16:33           ` Wilco Dijkstra
2023-01-16 17:01             ` Noah Goldstein
2023-01-16 18:35               ` Wilco Dijkstra
2023-01-12 15:11 ` Zack Weinberg

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