* [PATCH] eal/x86: fix TSC frequency query
@ 2026-01-30 17:10 Thomas Monjalon
2026-01-30 18:15 ` Stephen Hemminger
0 siblings, 1 reply; 3+ messages in thread
From: Thomas Monjalon @ 2026-01-30 17:10 UTC (permalink / raw)
To: dev
Cc: stable, Luigi Rizzo, Bruce Richardson, Konstantin Ananyev,
Sergio Gonzalez Monroy, Harry van Haaren
After getting TSC information from cpuid instruction,
some values must be multiplied and divided.
We must multiply first to get the most accurate value.
Example:
before: 1000000000 * (23 / 10) = 2 GHz
after: 1000000000 * 23 / 10 = 2.3 GHz
Bugzilla ID: 1869
Fixes: ad3516bb4ae1 ("eal/x86: implement arch-specific TSC freq query")
Cc: stable@dpdk.org
Reported-by: Luigi Rizzo <rizzo.unipi@gmail.com>
Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
---
lib/eal/x86/rte_cycles.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/eal/x86/rte_cycles.c b/lib/eal/x86/rte_cycles.c
index f147a5231d..e8e805e710 100644
--- a/lib/eal/x86/rte_cycles.c
+++ b/lib/eal/x86/rte_cycles.c
@@ -145,7 +145,7 @@ get_tsc_freq_arch(void)
/* EBX : TSC/Crystal ratio, ECX : Crystal Hz */
if (b && c)
- return c * (b / a);
+ return (uint64_t)c * b / a;
}
#ifdef RTE_TOOLCHAIN_MSVC
--
2.52.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] eal/x86: fix TSC frequency query
2026-01-30 17:10 [PATCH] eal/x86: fix TSC frequency query Thomas Monjalon
@ 2026-01-30 18:15 ` Stephen Hemminger
2026-02-03 11:08 ` Thomas Monjalon
0 siblings, 1 reply; 3+ messages in thread
From: Stephen Hemminger @ 2026-01-30 18:15 UTC (permalink / raw)
To: Thomas Monjalon
Cc: dev, stable, Luigi Rizzo, Bruce Richardson, Konstantin Ananyev,
Sergio Gonzalez Monroy, Harry van Haaren
On Fri, 30 Jan 2026 18:10:26 +0100
Thomas Monjalon <thomas@monjalon.net> wrote:
> After getting TSC information from cpuid instruction,
> some values must be multiplied and divided.
> We must multiply first to get the most accurate value.
>
> Example:
> before: 1000000000 * (23 / 10) = 2 GHz
> after: 1000000000 * 23 / 10 = 2.3 GHz
>
> Bugzilla ID: 1869
> Fixes: ad3516bb4ae1 ("eal/x86: implement arch-specific TSC freq query")
> Cc: stable@dpdk.org
>
> Reported-by: Luigi Rizzo <rizzo.unipi@gmail.com>
> Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Reviewed-by: Stephen Hemminger <stephen@networkplumber.org>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] eal/x86: fix TSC frequency query
2026-01-30 18:15 ` Stephen Hemminger
@ 2026-02-03 11:08 ` Thomas Monjalon
0 siblings, 0 replies; 3+ messages in thread
From: Thomas Monjalon @ 2026-02-03 11:08 UTC (permalink / raw)
To: Luigi Rizzo
Cc: dev, stable, Bruce Richardson, Konstantin Ananyev,
Sergio Gonzalez Monroy, Harry van Haaren, Stephen Hemminger
30/01/2026 19:15, Stephen Hemminger:
> On Fri, 30 Jan 2026 18:10:26 +0100
> Thomas Monjalon <thomas@monjalon.net> wrote:
>
> > After getting TSC information from cpuid instruction,
> > some values must be multiplied and divided.
> > We must multiply first to get the most accurate value.
> >
> > Example:
> > before: 1000000000 * (23 / 10) = 2 GHz
> > after: 1000000000 * 23 / 10 = 2.3 GHz
> >
> > Bugzilla ID: 1869
> > Fixes: ad3516bb4ae1 ("eal/x86: implement arch-specific TSC freq query")
> > Cc: stable@dpdk.org
> >
> > Reported-by: Luigi Rizzo <rizzo.unipi@gmail.com>
> > Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
>
> Reviewed-by: Stephen Hemminger <stephen@networkplumber.org>
Applied
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2026-02-03 11:08 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-01-30 17:10 [PATCH] eal/x86: fix TSC frequency query Thomas Monjalon
2026-01-30 18:15 ` Stephen Hemminger
2026-02-03 11:08 ` Thomas Monjalon
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.