> -----邮件原件----- > 发件人: Feifei Wang > 发送时间: Wednesday, October 20, 2021 10:46 AM > 收件人: David Marchand <david.march...@redhat.com> > 抄送: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>; dev > <dev@dpdk.org>; nd <n...@arm.com>; Ruifeng Wang > <ruifeng.w...@arm.com>; nd <n...@arm.com> > 主题: 回复: [dpdk-dev] [PATCH v1 2/2] mcslock: use wait until equal API for > tight loop > > > -----邮件原件----- > > 发件人: dev <dev-boun...@dpdk.org> 代表 David Marchand > > 发送时间: Tuesday, October 19, 2021 7:10 PM > > 收件人: Feifei Wang <feifei.wa...@arm.com> > > 抄送: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>; dev > > <dev@dpdk.org>; nd <n...@arm.com>; Ruifeng Wang > <ruifeng.w...@arm.com> > > 主题: Re: [dpdk-dev] [PATCH v1 2/2] mcslock: use wait until equal API > > for tight loop > > > > On Wed, Aug 25, 2021 at 10:02 AM Feifei Wang <feifei.wa...@arm.com> > > wrote: > > > > > > Instead of polling for previous lock holder unlocking, use > > > wait_until_equal API. > > > > > > Signed-off-by: Feifei Wang <feifei.wa...@arm.com> > > > Reviewed-by: Ruifeng Wang <ruifeng.w...@arm.com> > > > --- > > > lib/eal/include/generic/rte_mcslock.h | 4 ++-- > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > diff --git a/lib/eal/include/generic/rte_mcslock.h > > > b/lib/eal/include/generic/rte_mcslock.h > > > index 9f323bd2a2..c99343f22c 100644 > > > --- a/lib/eal/include/generic/rte_mcslock.h > > > +++ b/lib/eal/include/generic/rte_mcslock.h > > > @@ -84,8 +84,8 @@ rte_mcslock_lock(rte_mcslock_t **msl, > > rte_mcslock_t *me) > > > * to spin on me->locked until the previous lock holder resets > > > * the me->locked using mcslock_unlock(). > > > */ > > > - while (__atomic_load_n(&me->locked, __ATOMIC_ACQUIRE)) > > > - rte_pause(); > > > + rte_wait_until_equal_32((volatile uint32_t *)&me->locked, > > > + 0, __ATOMIC_ACQUIRE); > > > > Why do you need to cast as volatile? > Thanks for the comments. > This is firstly because rte_wait_until_equal API defines the variable as > volatile. > However, with your comment, I find 'me->lock' is not volatile. And by the > test, > I think you are right, it is necessary to add volatile here.
Sorry, correct the writing mistakes: 'It is unnecessary to add volatile here.' > > > > > > -- > > David Marchand
