From: Conor Dooley <conor@kernel.org>
To: Atish Patra <atishp@atishpatra.org>
Cc: Heiko Stuebner <heiko@sntech.de>,
Conor Dooley <conor.dooley@microchip.com>,
Jessica Clarke <jrtc27@jrtc27.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
linux-riscv <linux-riscv@lists.infradead.org>,
Samuel Holland <samuel@sholland.org>,
Albert Ou <aou@eecs.berkeley.edu>,
Anup Patel <anup@brainfault.org>,
Atish Patra <atishp@rivosinc.com>, Dao Lu <daolu@rivosinc.com>,
Guo Ren <guoren@kernel.org>, Jisheng Zhang <jszhang@kernel.org>,
Paul Walmsley <paul.walmsley@sifive.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] riscv: Fix build with CONFIG_CC_OPTIMIZE_FOR_SIZE=y
Date: Tue, 4 Oct 2022 18:15:11 +0100 [thread overview]
Message-ID: <YzxqH095FxqKZpDg@spud> (raw)
In-Reply-To: <CAOnJCUKtoiXKaS81BZyvpybFDkh-undHLqE5ZxoNmf9AtAtvfw@mail.gmail.com>
On Tue, Oct 04, 2022 at 09:52:41AM -0700, Atish Patra wrote:
> On Sat, Oct 1, 2022 at 1:13 PM Conor Dooley <conor@kernel.org> wrote:
> > > Thanks. It would be good to understand what happens when "pause" is
> > > executed on these boards ?
> >
> > The actual pause instruction? uhh, so with the usual "I don't know what
> > I am doing" disclaimer, I ran each of the .insn and pause instruction 48
> > times in a row and checked the time elapsed via rdcycle & then ran that
> > c program 1000 times in a bash loop. Got the below, the insns were run
> > first and then the pauses.
> > insn pause
> > min 2.3 3.2
> > max 9.5 10.6
> > avg 27.0 29.1
> > 5% 2.9 4.2
> > 95% 18.1 19.1
> >
> > Swapping the pause & insn order around made a minor difference, but not
> > enough to report on. I'd be very wary of drawing any real conclusions
> > from this data, but at least both are roughly similar (and certainly not
> > even close to doing the div w/ zero args.
> >
>
> Yeah. That's what I was expecting. So we can't drop the div for now. Otherwise,
> the existing hardware(don't support Zhintpause) suffers by spinning faster.
>
> Thanks for running the experiments.
I've lost track, does that mean the patch is okay as, is or needs to be
changed? The former, right?
Thanks,
Conor.
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next prev parent reply other threads:[~2022-10-04 17:15 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-22 6:09 [PATCH] riscv: Fix build with CONFIG_CC_OPTIMIZE_FOR_SIZE=y Samuel Holland
2022-09-22 13:25 ` Conor Dooley
2022-09-22 15:45 ` Heiko Stuebner
2022-09-22 15:52 ` Jessica Clarke
2022-09-23 7:17 ` Heiko Stuebner
2022-09-23 18:01 ` Atish Patra
2022-09-24 23:15 ` Conor Dooley
2022-09-28 7:21 ` Atish Patra
2022-09-28 21:16 ` Conor Dooley
2022-09-29 3:26 ` Atish Patra
2022-10-01 20:13 ` Conor Dooley
2022-10-04 16:52 ` Atish Patra
2022-10-04 17:15 ` Conor Dooley [this message]
2022-10-04 17:24 ` Jessica Clarke
2022-10-05 0:38 ` Guo Ren
2022-10-05 1:01 ` Jessica Clarke
2022-10-05 1:40 ` Guo Ren
2022-10-05 14:25 ` Jessica Clarke
2022-10-06 6:48 ` Jisheng Zhang
2022-10-26 13:59 ` Palmer Dabbelt
2023-02-01 7:21 ` Palmer Dabbelt
2023-02-02 16:25 ` Jisheng Zhang
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