From: Alexey Dobriyan <adobriyan@gmail.com>
To: x86@kernel.org, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH 1/5] x86_64: use REP MOVSB in copy_page()
Date: Wed, 26 Apr 2017 21:23:19 +0300 [thread overview]
Message-ID: <20170426182318.GA5069@avx2> (raw)
On my Broadwell-era Xeon copying page with REP MOVSB is ~7.8% faster
than with REP MOVSQ. Choose REP MOVSB copy_page() at runtime
with alternatives.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
arch/x86/lib/copy_page_64.S | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
--- a/arch/x86/lib/copy_page_64.S
+++ b/arch/x86/lib/copy_page_64.S
@@ -13,13 +13,21 @@
*/
ALIGN
ENTRY(copy_page)
- ALTERNATIVE "jmp copy_page_regs", "", X86_FEATURE_REP_GOOD
+ ALTERNATIVE_2 "jmp copy_page_regs", \
+ "", X86_FEATURE_REP_GOOD, \
+ "jmp copy_page_rep_movsb", X86_FEATURE_ERMS
movl $4096/8, %ecx
rep movsq
ret
ENDPROC(copy_page)
EXPORT_SYMBOL(copy_page)
+ENTRY(copy_page_rep_movsb)
+ mov $4096, %ecx
+ rep movsb
+ ret
+ENDPROC(copy_page_rep_movsb)
+
ENTRY(copy_page_regs)
subq $2*8, %rsp
movq %rbx, (%rsp)
next reply other threads:[~2017-04-26 18:24 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-26 18:23 Alexey Dobriyan [this message]
2017-04-26 18:28 ` [PATCH 2/5] x86_64: inline copy_page() at call site Alexey Dobriyan
2017-04-26 18:30 ` [PATCH 3/5] x86_64: rename clear_page() and copy_user() variants Alexey Dobriyan
2017-04-26 18:34 ` [PATCH 4/5] x86_64: clobber "cc" in inlined clear_page() Alexey Dobriyan
2017-04-26 18:35 ` [PATCH 5/5] x86_64: garbage collect headers in clear_page.S Alexey Dobriyan
2017-05-05 16:58 ` [PATCH 3/5] x86_64: rename clear_page() and copy_user() variants Borislav Petkov
2017-04-28 21:04 ` [PATCH 2/5] x86_64: inline copy_page() at call site Borislav Petkov
2017-05-02 11:49 ` Alexey Dobriyan
2017-05-02 11:59 ` Borislav Petkov
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