From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Santosh Sivaraj <santosh@fossix.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 4/8] powerpc/vdso32: inline __get_datapage()
Date: Fri, 13 Sep 2019 12:59:31 +0200 [thread overview]
Message-ID: <a95c4a58-bc59-3e75-46db-414f6d0f1412@c-s.fr> (raw)
In-Reply-To: <87h864iiq9.fsf@santosiv.in.ibm.com>
Hi Santosh,
Le 26/08/2019 à 07:44, Santosh Sivaraj a écrit :
> Hi Christophe,
>
> Christophe Leroy <christophe.leroy@c-s.fr> writes:
>
>> __get_datapage() is only a few instructions to retrieve the
>> address of the page where the kernel stores data to the VDSO.
>>
>> By inlining this function into its users, a bl/blr pair and
>> a mflr/mtlr pair is avoided, plus a few reg moves.
>>
>> The improvement is noticeable (about 55 nsec/call on an 8xx)
>>
>> vdsotest before the patch:
>> gettimeofday: vdso: 731 nsec/call
>> clock-gettime-realtime-coarse: vdso: 668 nsec/call
>> clock-gettime-monotonic-coarse: vdso: 745 nsec/call
>>
>> vdsotest after the patch:
>> gettimeofday: vdso: 677 nsec/call
>> clock-gettime-realtime-coarse: vdso: 613 nsec/call
>> clock-gettime-monotonic-coarse: vdso: 690 nsec/call
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>> ---
>> arch/powerpc/kernel/vdso32/cacheflush.S | 10 +++++-----
>> arch/powerpc/kernel/vdso32/datapage.S | 29 ++++-------------------------
>> arch/powerpc/kernel/vdso32/datapage.h | 11 +++++++++++
>> arch/powerpc/kernel/vdso32/gettimeofday.S | 13 ++++++-------
>> 4 files changed, 26 insertions(+), 37 deletions(-)
>> create mode 100644 arch/powerpc/kernel/vdso32/datapage.h
>
> The datapage.h file should ideally be moved under include/asm, then we can use
> the same for powerpc64 too.
I have a more ambitious project indeed.
Most of the VDSO code is duplicated between vdso32 and vdso64. I'm
aiming at merging everything into a single source code.
This means we would have to generate vdso32.so and vdso64.so out of the
same source files. Any idea on how to do that ? I'm not too good at
creating Makefiles. I guess we would have everything in
arch/powerpc/kernel/vdso/ and would have to build the objects twice,
once in arch/powerpc/kernel/vdso32/ and once in arch/powerpc/kernel/vdso64/
Christophe
next prev parent reply other threads:[~2019-09-13 11:01 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-22 16:34 [PATCH v2 0/8] powerpc/vdso32 enhancement and optimisation Christophe Leroy
2019-08-22 16:34 ` [PATCH v2 1/8] powerpc/32: Add VDSO version of getcpu Christophe Leroy
2019-09-18 5:51 ` Michael Ellerman
2019-10-29 16:10 ` Christophe Leroy
2019-08-22 16:34 ` [PATCH v2 2/8] powerpc/vdso32: Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE Christophe Leroy
2019-08-22 16:34 ` [PATCH v2 3/8] powerpc: Fix vDSO clock_getres() Christophe Leroy
2019-08-22 17:17 ` Sasha Levin
2019-08-22 16:34 ` [PATCH v2 4/8] powerpc/vdso32: inline __get_datapage() Christophe Leroy
2019-08-26 5:44 ` Santosh Sivaraj
2019-09-13 10:59 ` Christophe Leroy [this message]
2019-09-13 13:31 ` Santosh Sivaraj
2019-09-13 13:50 ` Christophe Leroy
2019-09-13 14:03 ` Santosh Sivaraj
2019-10-29 16:12 ` Christophe Leroy
2019-08-22 16:34 ` [PATCH v2 5/8] powerpc/vdso32: Don't read cache line size from the datapage on PPC32 Christophe Leroy
2019-08-22 16:34 ` [PATCH v2 6/8] powerpc/vdso32: use LOAD_REG_IMMEDIATE() Christophe Leroy
2019-08-22 16:34 ` [PATCH v2 7/8] powerpc/vdso32: implement clock_getres entirely Christophe Leroy
2019-08-22 16:34 ` [PATCH v2 8/8] powerpc/vdso32: miscellaneous optimisations Christophe Leroy
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