From: bugzilla@dpdk.org
To: dev@dpdk.org
Subject: [DPDK/core Bug 1869] incorrect get_tsc_freq_arch() due to integer truncation
Date: Thu, 22 Jan 2026 18:03:47 +0000 [thread overview]
Message-ID: <bug-1869-3@http.bugs.dpdk.org/> (raw)
http://bugs.dpdk.org/show_bug.cgi?id=1869
Bug ID: 1869
Summary: incorrect get_tsc_freq_arch() due to integer
truncation
Product: DPDK
Version: unspecified
Hardware: x86
OS: All
Status: UNCONFIRMED
Severity: normal
Priority: Normal
Component: core
Assignee: dev@dpdk.org
Reporter: rizzo.unipi@gmail.com
Target Milestone: ---
There is a bug in
https://github.com/DPDK/dpdk/blob/main/lib/eal/x86/rte_cycles.c#L148
143 __cpuid(0x15, a, b, c, d);
...
146 /* EBX : TSC/Crystal ratio, ECX : Crystal Hz */
147 if (b && c)
148 return c * (b / a);
On one machine, line 143 returns a 10 b 23 c 1000000000 d 0,
the division (b / a) returns 2 hence leading to
an incorrect value (2 GHz instead of 2.3 GHz)
The trivial fix is to replace line 148 with
return (uint64_t)c * b / a;
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next reply other threads:[~2026-01-22 18:03 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-22 18:03 bugzilla [this message]
2026-02-17 22:03 ` [DPDK/core Bug 1869] incorrect get_tsc_freq_arch() due to integer truncation bugzilla
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