From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
arnd@arndb.de, tglx@linutronix.de, vincenzo.frascino@arm.com,
luto@kernel.org
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org,
x86@kernel.org
Subject: [RFC PATCH v3 09/12] powerpc/vdso: provide inline alternative to __get_datapage()
Date: Mon, 13 Jan 2020 17:08:47 +0000 (UTC) [thread overview]
Message-ID: <ecb0105333f0b95f233565e12282c451d99b2915.1578934751.git.christophe.leroy@c-s.fr> (raw)
In-Reply-To: <cover.1578934751.git.christophe.leroy@c-s.fr>
__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)
With current __get_datapage() function:
gettimeofday: vdso: 731 nsec/call
clock-gettime-realtime-coarse: vdso: 668 nsec/call
clock-gettime-monotonic-coarse: vdso: 745 nsec/call
Using the __get_datapage macro provided by this 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/include/asm/vdso_datapage.h | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/arch/powerpc/include/asm/vdso_datapage.h b/arch/powerpc/include/asm/vdso_datapage.h
index 4d7965bf369e..7342cc0c1ae4 100644
--- a/arch/powerpc/include/asm/vdso_datapage.h
+++ b/arch/powerpc/include/asm/vdso_datapage.h
@@ -105,6 +105,17 @@ struct vdso_arch_data {
extern struct vdso_arch_data *vdso_data;
+#else /* __ASSEMBLY__ */
+
+.macro get_datapage ptr, offset=0
+ bcl 20, 31, .+4
+ mflr \ptr
+#if CONFIG_PPC_PAGE_SHIFT > 14
+ addis \ptr, \ptr, (_vdso_datapage + \offset - (.-4))@ha
+#endif
+ addi \ptr, \ptr, (_vdso_datapage + \offset - (.-4))@l
+.endm
+
#endif /* __ASSEMBLY__ */
#endif /* __KERNEL__ */
--
2.13.3
next prev parent reply other threads:[~2020-01-13 17:09 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-13 17:08 [RFC PATCH v3 00/12] powerpc: switch VDSO to C implementation Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 01/12] powerpc/64: Don't provide time functions in compat VDSO32 Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 02/12] powerpc/vdso: Switch VDSO to generic C implementation Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 03/12] lib: vdso: mark __cvdso_clock_getres() as static Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 04/12] lib: vdso: inline do_hres() and do_coarse() Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 05/12] lib: vdso: Avoid duplication in __cvdso_clock_getres() Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 06/12] lib: vdso: __iter_div_u64_rem() is suboptimal for 32 bit time Christophe Leroy
2020-01-14 11:31 ` Thomas Gleixner
2020-01-13 17:08 ` [RFC PATCH v3 07/12] powerpc/vdso: simplify __get_datapage() Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 08/12] lib: vdso: allow arches to provide vdso data pointer Christophe Leroy
2020-01-14 23:06 ` Thomas Gleixner
2020-01-15 6:15 ` Christophe Leroy
2020-01-16 9:16 ` Christophe Leroy
2020-01-16 10:35 ` Thomas Gleixner
2020-01-16 20:22 ` Andy Lutomirski
2020-01-13 17:08 ` Christophe Leroy [this message]
2020-01-13 17:08 ` [RFC PATCH v3 10/12] powerpc/vdso: provide vdso data pointer from the ASM caller Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 11/12] lib: vdso: split clock verification out of __arch_get_hw_counter() Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 12/12] powerpc/vdso: provide __arch_is_hw_counter_valid() Christophe Leroy
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ecb0105333f0b95f233565e12282c451d99b2915.1578934751.git.christophe.leroy@c-s.fr \
--to=christophe.leroy@c-s.fr \
--cc=arnd@arndb.de \
--cc=benh@kernel.crashing.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mips@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=luto@kernel.org \
--cc=mpe@ellerman.id.au \
--cc=paulus@samba.org \
--cc=tglx@linutronix.de \
--cc=vincenzo.frascino@arm.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).