From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A0D4816419 for ; Sat, 16 Nov 2024 19:32:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731785569; cv=none; b=CuuzHVGcxeTqBg76x6wIwT1Ia2QQ+UZSfwlgavZiJT/5FNg/C8adnEmvSBe7nASBbSe4wy1fugR++x8MytdlI/Dnuy8K0jOAVPsXhffBur5ovRxuTUv/g3PGzY+ekD6HLQL+PDDbmR3BU1FyeVjc8BBmQQv7+OlOrY/10PfRYfo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731785569; c=relaxed/simple; bh=l+2VyFr12c1gLjpG/21qZnJHHcAPMqJfdwtNyzJNtCM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=DoL9IGEJO9fIxB0XHkSVpC11mLFrIgtkmJANSqbqRFqN6vEv721sWYKBU3k5/QLTxFX3dPWJk3dBYDwgQCkGcOLyyED8AdIENO5jGokw7+311EeSiDFfzhp8XT+WmyndY/nbFWi2x9qdMUQ1tNAYY8SGj8eb96wvKmDbDn9Lpfw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=PunmrEmr; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="PunmrEmr" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=eChOwQECLVJIHCvz2Glp/wxD9OrPGWmo7NV/iFNeswk=; b=PunmrEmrq9bsEDMrZU3b+AYqBS ehWXVHbBlZTeRl7Ufhwf2xA+D7ZWEhtwX7eJ8Y6qnbjpzlJI0MF7S4e8LoHMskWjpRmdlNb3bJe5H pOl/w9SR9l+hEyB4CYL39l/6eaefjBCiOxvLkBwb1hL+ryVYf4z5IpebAAajmUx0z046jWcNpXA1c mWe5C7Uhak3GBhdLHhfyUjBTVMMkRKx1FsZf0rhFJBmdwZJWDbdGMDtBiwVk++O6Itcwb7ptf9GXZ qQnK0G0syoxgVCqQzcd9y4KLsYN/8IgeJlobIKZg+NDATfJSWwHHFV3n9i2693V+8wBQd4TBJTdbu qUlNSICA==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1tCOX5-00000001Oms-1Hxf; Sat, 16 Nov 2024 19:32:36 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id DABC7300472; Sat, 16 Nov 2024 20:32:35 +0100 (CET) Date: Sat, 16 Nov 2024 20:32:35 +0100 From: Peter Zijlstra To: Changwoo Min Cc: tj@kernel.org, void@manifault.com, mingo@redhat.com, changwoo@igalia.com, kernel-dev@igalia.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/5] sched_ext: Manage the validity of scx_rq_clock Message-ID: <20241116193235.GQ22801@noisy.programming.kicks-ass.net> References: <20241116160126.29454-1-changwoo@igalia.com> <20241116160126.29454-3-changwoo@igalia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241116160126.29454-3-changwoo@igalia.com> On Sun, Nov 17, 2024 at 01:01:23AM +0900, Changwoo Min wrote: > An rq clock becomes valid when it is updated using update_rq_clock() > and invalidated when the rq is unlocked using rq_unpin_lock(). Also, > after long running operations -- ops.running() and ops.update_idle() -- > in a BPF scheduler, the sched_ext core invalidates the rq clock. > > Signed-off-by: Changwoo Min > --- > kernel/sched/core.c | 6 +++++- > kernel/sched/ext.c | 3 +++ > kernel/sched/sched.h | 2 +- > 3 files changed, 9 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index a910a5b4c274..d0eb58b6a2da 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -784,6 +784,7 @@ static void update_rq_clock_task(struct rq *rq, s64 delta) > void update_rq_clock(struct rq *rq) > { > s64 delta; > + u64 clock; > > lockdep_assert_rq_held(rq); > > @@ -795,11 +796,14 @@ void update_rq_clock(struct rq *rq) > SCHED_WARN_ON(rq->clock_update_flags & RQCF_UPDATED); > rq->clock_update_flags |= RQCF_UPDATED; > #endif > + clock = sched_clock_cpu(cpu_of(rq)); > + scx_rq_clock_update(rq, clock); It is not at all clear why you think you need to keep a second copy of that value. You like cache misses?