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From: luca abeni <luca.abeni@santannapisa.it>
To: Vineeth Remanan Pillai <vineeth@bitbyteword.org>
Cc: Juri Lelli <juri.lelli@redhat.com>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Joel Fernandes <joel@joelfernandes.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Valentin Schneider <vschneid@redhat.com>,
	Jonathan Corbet <corbet@lwn.net>,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org
Subject: Re: [PATCH 1/2] sched/deadline: accurate reclaim bandwidth for GRUB
Date: Tue, 9 May 2023 22:54:17 +0200	[thread overview]
Message-ID: <20230509225417.61d36733@nowhere> (raw)
In-Reply-To: <20230509224829.2fb547fd@nowhere>

On Tue, 9 May 2023 22:48:29 +0200
luca abeni <luca.abeni@santannapisa.it> wrote:

> Hi,
> 
> On Tue, 9 May 2023 15:29:21 -0400
> Vineeth Remanan Pillai <vineeth@bitbyteword.org> wrote:
> [...]
> > > Is this understanding correct?    
> > Yes, the above two details are correct. In addition to that, I think
> > the existing equation had a small bug:
> > GRUB paper says, running time is depreciated as
> >    "dq = -U dt" where U is running_bw.
> > This is assuming that the whole cpu bandwidth could be reclaimed.
> > But in our case, we cap at Umax. So the equation should be
> >    "dq = -(U/Umax) dt"  
> 
> Yes, this is the approximation I was mentioning... Instead of using a
> division, I approximated it with a different equation using a sum.

Sorry, ignore this comment (and the following); I misinterpreted the
code (and my old notes).

I do not understand why the "max{}" doe not work well, I need to double
think about it.


			Luca

  reply	other threads:[~2023-05-09 20:56 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-08 16:08 [PATCH 1/2] sched/deadline: accurate reclaim bandwidth for GRUB Vineeth Pillai
2023-05-08 16:08 ` [PATCH 2/2] Documentation: sched/deadline: Update GRUB description Vineeth Pillai
2023-05-10  8:05   ` Bagas Sanjaya
2023-05-09 11:25 ` [PATCH 1/2] sched/deadline: accurate reclaim bandwidth for GRUB luca abeni
2023-05-09 19:29   ` Vineeth Remanan Pillai
2023-05-09 20:48     ` luca abeni
2023-05-09 20:54       ` luca abeni [this message]
2023-05-10  3:53         ` Vineeth Remanan Pillai
2023-05-10  7:07           ` luca abeni
2023-05-10 15:50             ` Vineeth Remanan Pillai
2023-05-11  7:37               ` luca abeni
2023-05-11 18:34                 ` Vineeth Remanan Pillai
2023-05-11 20:03                   ` luca abeni
2023-05-11 20:40                     ` Vineeth Remanan Pillai
2023-05-15  2:56                       ` Vineeth Remanan Pillai

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