| Message ID | 149821531970.5914.6372373520013365573.stgit@Solace (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 06/23/2017 11:55 AM, Dario Faggioli wrote: > Nothing changed in `pahole` output, in terms of holes > and padding, but some fields have been moved, to put > related members in same cache line. > > Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com> Acked-by: George Dunlap <george.dunlap@citrix.com> > --- > Cc: Meng Xu <mengxu@cis.upenn.edu> > Cc: George Dunlap <george.dunlap@eu.citrix.com> > --- > xen/common/sched_rt.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff --git a/xen/common/sched_rt.c b/xen/common/sched_rt.c > index 1b30014..39f6bee 100644 > --- a/xen/common/sched_rt.c > +++ b/xen/common/sched_rt.c > @@ -171,11 +171,14 @@ static void repl_timer_handler(void *data); > struct rt_private { > spinlock_t lock; /* the global coarse-grained lock */ > struct list_head sdom; /* list of availalbe domains, used for dump */ > + > struct list_head runq; /* ordered list of runnable vcpus */ > struct list_head depletedq; /* unordered list of depleted vcpus */ > + > + struct timer *repl_timer; /* replenishment timer */ > struct list_head replq; /* ordered list of vcpus that need replenishment */ > + > cpumask_t tickled; /* cpus been tickled */ > - struct timer *repl_timer; /* replenishment timer */ > }; > > /* > @@ -185,10 +188,6 @@ struct rt_vcpu { > struct list_head q_elem; /* on the runq/depletedq list */ > struct list_head replq_elem; /* on the replenishment events list */ > > - /* Up-pointers */ > - struct rt_dom *sdom; > - struct vcpu *vcpu; > - > /* VCPU parameters, in nanoseconds */ > s_time_t period; > s_time_t budget; > @@ -198,6 +197,10 @@ struct rt_vcpu { > s_time_t last_start; /* last start time */ > s_time_t cur_deadline; /* current deadline for EDF */ > > + /* Up-pointers */ > + struct rt_dom *sdom; > + struct vcpu *vcpu; > + > unsigned flags; /* mark __RTDS_scheduled, etc.. */ > }; > >
On Fri, Jun 23, 2017 at 6:55 AM, Dario Faggioli <dario.faggioli@citrix.com> wrote: > > Nothing changed in `pahole` output, in terms of holes > and padding, but some fields have been moved, to put > related members in same cache line. > > Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com> > --- > Cc: Meng Xu <mengxu@cis.upenn.edu> > Cc: George Dunlap <george.dunlap@eu.citrix.com> > --- > xen/common/sched_rt.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff --git a/xen/common/sched_rt.c b/xen/common/sched_rt.c > index 1b30014..39f6bee 100644 > --- a/xen/common/sched_rt.c > +++ b/xen/common/sched_rt.c > @@ -171,11 +171,14 @@ static void repl_timer_handler(void *data); > struct rt_private { > spinlock_t lock; /* the global coarse-grained lock */ > struct list_head sdom; /* list of availalbe domains, used for dump */ > + > struct list_head runq; /* ordered list of runnable vcpus */ > struct list_head depletedq; /* unordered list of depleted vcpus */ > + > + struct timer *repl_timer; /* replenishment timer */ > struct list_head replq; /* ordered list of vcpus that need replenishment */ > + > cpumask_t tickled; /* cpus been tickled */ > - struct timer *repl_timer; /* replenishment timer */ > }; > > /* > @@ -185,10 +188,6 @@ struct rt_vcpu { > struct list_head q_elem; /* on the runq/depletedq list */ > struct list_head replq_elem; /* on the replenishment events list */ > > - /* Up-pointers */ > - struct rt_dom *sdom; > - struct vcpu *vcpu; > - > /* VCPU parameters, in nanoseconds */ > s_time_t period; > s_time_t budget; > @@ -198,6 +197,10 @@ struct rt_vcpu { > s_time_t last_start; /* last start time */ > s_time_t cur_deadline; /* current deadline for EDF */ > > + /* Up-pointers */ > + struct rt_dom *sdom; > + struct vcpu *vcpu; > + > unsigned flags; /* mark __RTDS_scheduled, etc.. */ > }; > Reviewed-by: Meng Xu <mengxu@cis.upenn.edu> BTW, Dario, I'm wondering if you used any tool to give hints about how to arrange the fields in a structure or you just did it manually? Thanks, Meng ----------- Meng Xu PhD Candidate in Computer and Information Science University of Pennsylvania http://www.cis.upenn.edu/~mengxu/
On Fri, 2017-07-21 at 13:51 -0400, Meng Xu wrote: > On Fri, Jun 23, 2017 at 6:55 AM, Dario Faggioli > <dario.faggioli@citrix.com> wrote: > > > > Nothing changed in `pahole` output, in terms of holes > > and padding, but some fields have been moved, to put > > related members in same cache line. > > > > Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com> > > --- > > Cc: Meng Xu <mengxu@cis.upenn.edu> > > Cc: George Dunlap <george.dunlap@eu.citrix.com> > > --- > > xen/common/sched_rt.c | 13 ++++++++----- > > 1 file changed, 8 insertions(+), 5 deletions(-) > > > > diff --git a/xen/common/sched_rt.c b/xen/common/sched_rt.c > > index 1b30014..39f6bee 100644 > > --- a/xen/common/sched_rt.c > > +++ b/xen/common/sched_rt.c > > @@ -171,11 +171,14 @@ static void repl_timer_handler(void *data); > > struct rt_private { > > spinlock_t lock; /* the global coarse-grained lock > > */ > > struct list_head sdom; /* list of availalbe domains, used > > for dump */ > > + > > struct list_head runq; /* ordered list of runnable vcpus > > */ > > struct list_head depletedq; /* unordered list of depleted > > vcpus */ > > + > > + struct timer *repl_timer; /* replenishment timer */ > > struct list_head replq; /* ordered list of vcpus that need > > replenishment */ > > + > > cpumask_t tickled; /* cpus been tickled */ > > - struct timer *repl_timer; /* replenishment timer */ > > }; > > > > /* > > @@ -185,10 +188,6 @@ struct rt_vcpu { > > struct list_head q_elem; /* on the runq/depletedq list */ > > struct list_head replq_elem; /* on the replenishment events > > list */ > > > > - /* Up-pointers */ > > - struct rt_dom *sdom; > > - struct vcpu *vcpu; > > - > > /* VCPU parameters, in nanoseconds */ > > s_time_t period; > > s_time_t budget; > > @@ -198,6 +197,10 @@ struct rt_vcpu { > > s_time_t last_start; /* last start time */ > > s_time_t cur_deadline; /* current deadline for EDF */ > > > > + /* Up-pointers */ > > + struct rt_dom *sdom; > > + struct vcpu *vcpu; > > + > > unsigned flags; /* mark __RTDS_scheduled, etc.. > > */ > > }; > > > > Reviewed-by: Meng Xu <mengxu@cis.upenn.edu> > > BTW, Dario, I'm wondering if you used any tool to give hints about > how > to arrange the fields in a structure or you just did it manually? > I used pahole for figuring out the cache layout. But just that. So, basically, I --manually-- tried to move the fields around, and check the result with pahole (and then did it again, and again. :-D). TBH, the improvement for RTDS is probably not even noticeable, as we access almost all the fields anyway. But it still makes sense, IMO. Thanks for the review, Dario
diff --git a/xen/common/sched_rt.c b/xen/common/sched_rt.c index 1b30014..39f6bee 100644 --- a/xen/common/sched_rt.c +++ b/xen/common/sched_rt.c @@ -171,11 +171,14 @@ static void repl_timer_handler(void *data); struct rt_private { spinlock_t lock; /* the global coarse-grained lock */ struct list_head sdom; /* list of availalbe domains, used for dump */ + struct list_head runq; /* ordered list of runnable vcpus */ struct list_head depletedq; /* unordered list of depleted vcpus */ + + struct timer *repl_timer; /* replenishment timer */ struct list_head replq; /* ordered list of vcpus that need replenishment */ + cpumask_t tickled; /* cpus been tickled */ - struct timer *repl_timer; /* replenishment timer */ }; /* @@ -185,10 +188,6 @@ struct rt_vcpu { struct list_head q_elem; /* on the runq/depletedq list */ struct list_head replq_elem; /* on the replenishment events list */ - /* Up-pointers */ - struct rt_dom *sdom; - struct vcpu *vcpu; - /* VCPU parameters, in nanoseconds */ s_time_t period; s_time_t budget; @@ -198,6 +197,10 @@ struct rt_vcpu { s_time_t last_start; /* last start time */ s_time_t cur_deadline; /* current deadline for EDF */ + /* Up-pointers */ + struct rt_dom *sdom; + struct vcpu *vcpu; + unsigned flags; /* mark __RTDS_scheduled, etc.. */ };
Nothing changed in `pahole` output, in terms of holes and padding, but some fields have been moved, to put related members in same cache line. Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com> --- Cc: Meng Xu <mengxu@cis.upenn.edu> Cc: George Dunlap <george.dunlap@eu.citrix.com> --- xen/common/sched_rt.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-)