----- On Feb 16, 2022, at 2:35 AM, lttng-dev lttng-dev@lists.lttng.org wrote:
> It is enough to have three values of rcu_gp.ctr, 00 for INACTIVE, > 01 or 11 for ACTIVE. So it is possible to replace add operation > with xor operation when changing rcu_gp.ctr value. What is missing here is a description justifying why this change is useful. What is inherently better about XOR compared to ADD or even binary-OR ? If it's about performance, then a benchmark on relevant architectures would be useful. But I suspect that if end users care that much about the performance of urcu_qsbr_synchronize_rcu(), they might be doing something wrong. Thanks, Mathieu > > Signed-off-by: yaowenbin <yaowenb...@huawei.com> > --- > src/urcu-qsbr.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/src/urcu-qsbr.c b/src/urcu-qsbr.c > index 3709412..46135f9 100644 > --- a/src/urcu-qsbr.c > +++ b/src/urcu-qsbr.c > @@ -391,7 +391,7 @@ void urcu_qsbr_synchronize_rcu(void) > goto out; > > /* Increment current G.P. */ > - CMM_STORE_SHARED(urcu_qsbr_gp.ctr, urcu_qsbr_gp.ctr + URCU_QSBR_GP_CTR); > + CMM_STORE_SHARED(urcu_qsbr_gp.ctr, urcu_qsbr_gp.ctr ^ URCU_QSBR_GP_CTR); > > /* > * Must commit urcu_qsbr_gp.ctr update to memory before waiting for > -- > 2.27.0 > _______________________________________________ > lttng-dev mailing list > lttng-dev@lists.lttng.org > https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
