Messages in this thread | | | Date | Wed, 05 Jun 2013 13:26:50 +0800 | From | Michael Wang <> | Subject | Re: [PATCH 1/2] sched: Optimize build_sched_domains() for saving first SD node for a cpu |
| |
On 06/05/2013 01:07 PM, Viresh Kumar wrote: > On 5 June 2013 10:12, Michael Wang <wangyun@linux.vnet.ibm.com> wrote: >> Hi, Viresh >> >> On 06/04/2013 07:20 PM, Viresh Kumar wrote: >> [snip] >>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c >>> index 58453b8..638f6cb 100644 >>> --- a/kernel/sched/core.c >>> +++ b/kernel/sched/core.c >>> @@ -6533,16 +6533,13 @@ static int build_sched_domains(const struct cpumask *cpu_map, >>> sd = NULL; >>> for (tl = sched_domain_topology; tl->init; tl++) { >>> sd = build_sched_domain(tl, &d, cpu_map, attr, sd, i); >>> + if (!*per_cpu_ptr(d.sd, i)) >> >> What about: >> if (tl == sched_domain_topology) >> >> It cost less than per_cpu_ptr(), isn't it? > > How can I miss it.. Obviously its better :) > > See if below one looks better (Attached too in case gmail screws up > my mail)..
Looks good to me :)
Regards, Michael Wang
> > --------x-------------x------------------ > > From: Viresh Kumar <viresh.kumar@linaro.org> > Date: Tue, 4 Jun 2013 15:41:15 +0530 > Subject: [PATCH] sched: Optimize build_sched_domains() for saving first SD > node for a cpu > > We are saving first scheduling domain for a cpu in build_sched_domains() by > iterating over the nested sd->child list. We don't actually need to do it this > way. > > tl will be equal to sched_domain_topology for the first iteration and so we can > set *per_cpu_ptr(d.sd, i) based on that. So, save pointer to first SD while > running the iteration loop over tl's. > > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> > --- > kernel/sched/core.c | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 58453b8..08a27be 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -6533,16 +6533,13 @@ static int build_sched_domains(const struct > cpumask *cpu_map, > sd = NULL; > for (tl = sched_domain_topology; tl->init; tl++) { > sd = build_sched_domain(tl, &d, cpu_map, attr, sd, i); > + if (tl == sched_domain_topology) > + *per_cpu_ptr(d.sd, i) = sd; > if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP)) > sd->flags |= SD_OVERLAP; > if (cpumask_equal(cpu_map, sched_domain_span(sd))) > break; > } > - > - while (sd->child) > - sd = sd->child; > - > - *per_cpu_ptr(d.sd, i) = sd; > } > > /* Build the groups for the domains */ >
| |