On 5 June 2013 10:12, Michael Wang <[email protected]> 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).. --------x-------------x------------------ From: Viresh Kumar <[email protected]> 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 <[email protected]> --- 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 */
0001-sched-Optimize-build_sched_domains-for-saving-first-.patch
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