From: Stephen Hemminger <stephen@networkplumber.org>
To: Hari Haran <info2hariharan@gmail.com>
Cc: users@dpdk.org
Subject: Re: rte_rdtsc() - what is the performance impact of using rte_rdtsc() time
Date: Tue, 3 Oct 2023 10:17:58 -0700 [thread overview]
Message-ID: <20231003101758.212f1352@hermes.local> (raw)
In-Reply-To: <CAPbxCtpjzFRhPNUk_35qS3U8fxAUkCWGcXm0+fqPOPmvsNXBtQ@mail.gmail.com>
On Tue, 3 Oct 2023 15:49:00 +0530
Hari Haran <info2hariharan@gmail.com> wrote:
> >
> > The problem is that rte_rdtsc() stops speculative execution so doing
> > lots of TSC instructions can hurt performance.
> >
> > To correlate TSC timestamp to system time, you need to compute the offsets
> > once at startup. Alternatively, don't use rte_rdtsc() and instead use
> > clock_gettime() with the monotonic timer and the C library does the
> > calculation
> > for you.
> >
>
>
> As part of query 1 and based on your response, I am asking below query
>
> But usage of clock_gettime() (kernel function) in lcore is advisable one?
> My understanding is,
> shall avoid usage of kernel function in lcore. Correct me if I am wrong?
clock_gettime() is a virtual system call (VDSO) on most Linux platforms.
But it is still slower than simple rte_rdtsc().
Internally clock_gettime VDSO
prev parent reply other threads:[~2023-10-03 17:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-29 14:55 Hari Haran
2023-09-05 23:29 ` Stephen Hemminger
2023-10-03 10:19 ` Hari Haran
2023-10-03 17:17 ` Stephen Hemminger [this message]
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