-----邮件原件----- 发件人: Jerin Jacob [mailto:[email protected]] 发送时间: 2020年3月9日 23:43 收件人: Linhaifeng <[email protected]> 抄送: [email protected]; [email protected]; Lilijun (Jerry) <[email protected]>; chenchanghu <[email protected]>; xudingke <[email protected]> 主题: Re: [dpdk-dev] [PATCH] cycles: add isb before read cntvct_el0
On Mon, Mar 9, 2020 at 2:43 PM Linhaifeng <[email protected]> wrote: > > We nead isb rather than dsb to sync system counter to cntvct_el0. # Currently rte_rdtsc() does not have dsb. Right? or any barriers. # Why do you need it? If it regarding, getting accurate value then use rte_rdtsc_precise(). We use rte_get_tsc_cycles get start_value in pmd1 and end_value in pmd2 in our qos module, it works ok in x86 but not ok in arm64. Then we use rte_mb() to sync instruction but it not work.Because rte_mb is dsb I think it only have affect on memory. cntvct_el0 and system counter is register so I think we should use isb. It works well after we use isb in multi core scenes. Use rte_rdtsc_precise is good idea. Maybe use isb replace of rte_mb(dsb) ? > > Signed-off-by: Haifeng Lin <[email protected]>
