Messages in this thread | | | Date | Thu, 11 Apr 2024 09:28:04 +0200 | Subject | Re: [PATCH V6 1/6] sched/fair: Add trivial fair server | From | Daniel Bristot de Oliveira <> |
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On 4/10/24 19:24, Peter Zijlstra wrote: > On Fri, Apr 05, 2024 at 07:28:00PM +0200, Daniel Bristot de Oliveira wrote: >> From: Peter Zijlstra <peterz@infradead.org> >> >> Use deadline servers to service fair tasks. >> >> This patch adds a fair_server deadline entity which acts as a container >> for fair entities and can be used to fix starvation when higher priority >> (wrt fair) tasks are monopolizing CPU(s). >> >> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> >> Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org> >> --- >> kernel/sched/core.c | 24 ++++++++++++++++-------- >> kernel/sched/deadline.c | 23 +++++++++++++++++++++++ >> kernel/sched/fair.c | 25 +++++++++++++++++++++++++ >> kernel/sched/sched.h | 4 ++++ >> 4 files changed, 68 insertions(+), 8 deletions(-) >> >> diff --git a/kernel/sched/core.c b/kernel/sched/core.c >> index 7019a40457a6..04e2270487b7 100644 >> --- a/kernel/sched/core.c >> +++ b/kernel/sched/core.c >> @@ -6007,6 +6007,14 @@ static void put_prev_task_balance(struct rq *rq, struct task_struct *prev, >> #endif >> >> put_prev_task(rq, prev); >> + >> + /* >> + * We've updated @prev and no longer need the server link, clear it. >> + * Must be done before ->pick_next_task() because that can (re)set >> + * ->dl_server. >> + */ >> + if (prev->dl_server) >> + prev->dl_server = NULL; >> } >> >> /* >> @@ -6037,6 +6045,13 @@ __pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) >> p = pick_next_task_idle(rq); >> } >> >> + /* >> + * This is a normal CFS pick, but the previous could be a DL pick. >> + * Clear it as previous is no longer picked. >> + */ >> + if (prev->dl_server) >> + prev->dl_server = NULL; >> + >> /* >> * This is the fast path; it cannot be a DL server pick; >> * therefore even if @p == @prev, ->dl_server must be NULL. >> @@ -6050,14 +6065,6 @@ __pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) >> restart: >> put_prev_task_balance(rq, prev, rf); >> >> - /* >> - * We've updated @prev and no longer need the server link, clear it. >> - * Must be done before ->pick_next_task() because that can (re)set >> - * ->dl_server. >> - */ >> - if (prev->dl_server) >> - prev->dl_server = NULL; >> - >> for_each_class(class) { >> p = class->pick_next_task(rq); >> if (p) > > This bit seems like a fix for 63ba8422f876 ("sched/deadline: Introduce > deadline servers"), should it be a separate patch?
It was actually reported in a separated patch as a pre-review of this series. So I think you can pick them as fixes already from there, and add the fixes tag?
https://lore.kernel.org/lkml/20240313012451.1693807-2-joel@joelfernandes.org/ https://lore.kernel.org/lkml/20240313012451.1693807-3-joel@joelfernandes.org/
Also add the Reviewed-by me...
-- Daniel
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