From: Sudeep Holla <sudeep.holla@arm.com>
To: Jassi Brar <jassisinghbrar@gmail.com>
Cc: Rob Herring <robh@kernel.org>, "arnd@arndb.de" <arnd@arndb.de>,
Viresh Kumar <viresh.kumar@linaro.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Jassi Brar <jaswinder.singh@linaro.org>,
Sudeep Holla <sudeep.holla@arm.com>,
Frank Rowand <frowand.list@gmail.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] firmware: arm_scmi: fix timeout value for send_message
Date: Thu, 11 Jun 2020 09:40:14 +0100 [thread overview]
Message-ID: <20200611084014.GB7357@bogus> (raw)
In-Reply-To: <CABb+yY0pQYD7DTf=MNpVPB7F2PESiWyTYj=ftRHDPkKMOobRVQ@mail.gmail.com>
On Wed, Jun 10, 2020 at 09:45:55PM -0500, Jassi Brar wrote:
> On Wed, Jun 10, 2020 at 10:56 AM Sudeep Holla <sudeep.holla@arm.com> wrote:
>
> [I admit you can write bigger posts than me, so I am not going to
> write a passionate response to each of your paragraphs.
> Let's keep it to the point.]
>
> > > > > if (xfer->hdr.poll_completion) {
> > > > > - ktime_t stop = ktime_add_ns(ktime_get(), SCMI_MAX_POLL_TO_NS);
> > > > > + ktime_t stop = ktime_add_ns(ktime_get(), 500 * 1000 * NSEC_PER_USEC);
> > > > >
> > > >
> > > > This is unacceptable delay for schedutil fast_switch. So no for this one.
> > > >
> > > Increasing timeout does not increase latency.
> >
> > Agreed, but worst case you may be stuck here for 500ms which is not
> > acceptable.
> >
> Not acceptable to who, you or the kernel? :) Now that you said you
> are fixing the scmi's fast_switch implementation.
>
Sorry, I meant to disable it for single channel implementation. I am not
saying we want that on Juno/MHU.
> Even though I don't think 500ms would ruin our lives, but ok, I will
> make it 30ms - same as you did in the 'else' block. And drop the other
> change.
I am fine if cpufreq maintainers allow that in the fast switch path that
happens in the fast path.
--
Regards,
Sudeep
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WARNING: multiple messages have this Message-ID (diff)
From: Sudeep Holla <sudeep.holla@arm.com>
To: Jassi Brar <jassisinghbrar@gmail.com>
Cc: linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
Rob Herring <robh@kernel.org>,
Frank Rowand <frowand.list@gmail.com>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
"arnd@arndb.de" <arnd@arndb.de>,
Sudeep Holla <sudeep.holla@arm.com>,
Jassi Brar <jaswinder.singh@linaro.org>
Subject: Re: [PATCH] firmware: arm_scmi: fix timeout value for send_message
Date: Thu, 11 Jun 2020 09:40:14 +0100 [thread overview]
Message-ID: <20200611084014.GB7357@bogus> (raw)
In-Reply-To: <CABb+yY0pQYD7DTf=MNpVPB7F2PESiWyTYj=ftRHDPkKMOobRVQ@mail.gmail.com>
On Wed, Jun 10, 2020 at 09:45:55PM -0500, Jassi Brar wrote:
> On Wed, Jun 10, 2020 at 10:56 AM Sudeep Holla <sudeep.holla@arm.com> wrote:
>
> [I admit you can write bigger posts than me, so I am not going to
> write a passionate response to each of your paragraphs.
> Let's keep it to the point.]
>
> > > > > if (xfer->hdr.poll_completion) {
> > > > > - ktime_t stop = ktime_add_ns(ktime_get(), SCMI_MAX_POLL_TO_NS);
> > > > > + ktime_t stop = ktime_add_ns(ktime_get(), 500 * 1000 * NSEC_PER_USEC);
> > > > >
> > > >
> > > > This is unacceptable delay for schedutil fast_switch. So no for this one.
> > > >
> > > Increasing timeout does not increase latency.
> >
> > Agreed, but worst case you may be stuck here for 500ms which is not
> > acceptable.
> >
> Not acceptable to who, you or the kernel? :) Now that you said you
> are fixing the scmi's fast_switch implementation.
>
Sorry, I meant to disable it for single channel implementation. I am not
saying we want that on Juno/MHU.
> Even though I don't think 500ms would ruin our lives, but ok, I will
> make it 30ms - same as you did in the 'else' block. And drop the other
> change.
I am fine if cpufreq maintainers allow that in the fast switch path that
happens in the fast path.
--
Regards,
Sudeep
next prev parent reply other threads:[~2020-06-11 8:40 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-07 19:30 [PATCH] firmware: arm_scmi: fix timeout value for send_message jassisinghbrar
2020-06-07 19:30 ` jassisinghbrar
2020-06-10 8:23 ` Sudeep Holla
2020-06-10 8:23 ` Sudeep Holla
2020-06-10 15:21 ` Jassi Brar
2020-06-10 15:21 ` Jassi Brar
2020-06-10 15:56 ` Sudeep Holla
2020-06-10 15:56 ` Sudeep Holla
2020-06-11 2:45 ` Jassi Brar
2020-06-11 2:45 ` Jassi Brar
2020-06-11 8:40 ` Sudeep Holla [this message]
2020-06-11 8:40 ` Sudeep Holla
2020-06-11 15:19 ` Jassi Brar
2020-06-11 15:19 ` Jassi Brar
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