On Tue, 4 Jul 2023 10:43:40 +0200 Morten Brørup <[email protected]> wrote:
> > From: Stephen Hemminger [mailto:[email protected]] > > Sent: Tuesday, 4 July 2023 01.24 > > > > RTE_ALIGN_MUL_NEAR is a macro so the cycle argument could > > get evaluated twice causing some potential skew. Fix by > > computing value once. > > > > Suggested by patch to fix side effects. > > > > Fixes: 5cbd14b3e5f9 ("eal: roundup TSC frequency when estimating") > > Cc: [email protected] > > Signed-off-by: Stephen Hemminger <[email protected]> > > --- > > v2 - fix spelling error in commit message > > > > lib/eal/common/eal_common_timer.c | 8 ++++++-- > > 1 file changed, 6 insertions(+), 2 deletions(-) > > > > diff --git a/lib/eal/common/eal_common_timer.c > > b/lib/eal/common/eal_common_timer.c > > index 5686a5102b66..05614b0503cf 100644 > > --- a/lib/eal/common/eal_common_timer.c > > +++ b/lib/eal/common/eal_common_timer.c > > @@ -42,10 +42,14 @@ estimate_tsc_freq(void) > > RTE_LOG(WARNING, EAL, "WARNING: TSC frequency estimated roughly" > > " - clock timings may be less accurate.\n"); > > /* assume that the rte_delay_us_sleep() will sleep for 1 second */ > > - uint64_t start = rte_rdtsc(); > > + uint64_t start, elapsed; > > + > > + start = rte_rdtsc(); > > rte_delay_us_sleep(US_PER_S); > > + elapsed = rte_rdtsc() - start; > > + > > /* Round up to 10Mhz. 1E7 ~ 10Mhz */ > > - return RTE_ALIGN_MUL_NEAR(rte_rdtsc() - start, CYC_PER_10MHZ); > > + return RTE_ALIGN_MUL_NEAR(elapsed, CYC_PER_10MHZ); > > } > > > > void > > -- > > 2.39.2 > > Please fix the RTE_ALIGN_MUL_NEAR() macro instead. It already uses temporary > variables with typeof() anyway. > > Other macros might have similar behavior of using their parameters more than > once, and could be improved too. > It is already fixed, so this patch can be dropped.
