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From: Segher Boessenkool <segher@kernel.crashing.org>
To: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: nathanl@linux.ibm.com, arnd@arndb.de, x86@kernel.org,
	linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org,
	Paul Mackerras <paulus@samba.org>,
	luto@kernel.org, tglx@linutronix.de, vincenzo.frascino@arm.com,
	linuxppc-dev@lists.ozlabs.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC PATCH v4 00/11] powerpc: switch VDSO to C implementation.
Date: Fri, 17 Jan 2020 02:58:51 -0600
Message-ID: <20200117085851.GS3191@gate.crashing.org> (raw)
In-Reply-To: <cover.1579196675.git.christophe.leroy@c-s.fr>

Hi!

On Thu, Jan 16, 2020 at 05:58:24PM +0000, Christophe Leroy wrote:
> On a powerpc8xx, with current powerpc/32 ASM VDSO:
> 
> gettimeofday:    vdso: 907 nsec/call
> clock-getres-realtime:    vdso: 484 nsec/call
> clock-gettime-realtime:    vdso: 899 nsec/call
> 
> The first patch adds VDSO generic C support without any changes to common code.
> Performance is as follows:
> 
> gettimeofday:    vdso: 1211 nsec/call
> clock-getres-realtime:    vdso: 722 nsec/call
> clock-gettime-realtime:    vdso: 1216 nsec/call
> 
> Then a few changes in the common code have allowed performance improvement. At
> the end of the series we have:
> 
> gettimeofday:    vdso: 974 nsec/call
> clock-getres-realtime:    vdso: 545 nsec/call
> clock-gettime-realtime:    vdso: 941 nsec/call
> 
> The final result is rather close to pure ASM VDSO:
> * 7% more on gettimeofday (9 cycles)
> * 5% more on clock-gettime-realtime (6 cycles)
> * 12% more on clock-getres-realtime (8 cycles)

Nice!  Much better.

It should be tested on more representative hardware, too, but this looks
promising alright :-)


Segher

  parent reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-16 17:58 Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 01/11] powerpc/64: Don't provide time functions in compat VDSO32 Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 02/11] powerpc/vdso: Switch VDSO to generic C implementation Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 03/11] lib: vdso: only read hrtimer_res when needed in __cvdso_clock_getres() Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 04/11] powerpc/vdso: simplify __get_datapage() Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 05/11] lib: vdso: allow arches to provide vdso data pointer Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 06/11] powerpc/vdso: provide inline alternative to __get_datapage() Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 07/11] powerpc/vdso: provide vdso data pointer from the ASM caller Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 08/11] lib: vdso: allow fixed clock mode Christophe Leroy
2020-01-16 20:13   ` Thomas Gleixner
2020-01-16 20:19     ` Andy Lutomirski
2020-01-16 21:07       ` Thomas Gleixner
2020-01-16 17:58 ` [RFC PATCH v4 09/11] powerpc/vdso: override __arch_vdso_capable() Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 10/11] lib: vdso: Allow arches to override the ns shift operation Christophe Leroy
2020-01-16 19:47   ` Andy Lutomirski
2020-01-16 19:57     ` Thomas Gleixner
2020-01-16 20:20       ` Andy Lutomirski
2020-01-29  7:14         ` Thomas Gleixner
2020-01-29  7:26           ` Christophe Leroy
2020-01-16 17:58 ` [RFC PATCH v4 11/11] powerpc/32: provide vdso_shift_ns() Christophe Leroy
2020-01-17  8:58 ` Segher Boessenkool [this message]
2020-01-17  9:26   ` [RFC PATCH v4 00/11] powerpc: switch VDSO to C implementation Christophe Leroy
2020-01-20 14:56   ` Christophe Leroy
2020-01-20 15:19     ` Segher Boessenkool
2020-01-20 17:08       ` Christophe Leroy
2020-01-20 17:27         ` Segher Boessenkool

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