From: Michael Ellerman <mpe@ellerman.id.au>
To: Andrey Abramov <st5pub@yandex.ru>, vgupta <vgupta@synopsys.com>,
benh <benh@kernel.crashing.org>, paulus <paulus@samba.org>,
tglx <tglx@linutronix.de>, mingo <mingo@redhat.com>,
bp <bp@alien8.de>, hpa <hpa@zytor.com>, x86 <x86@kernel.org>,
mark <mark@fasheh.com>, jlbec <jlbec@evilplan.org>,
richard <richard@nod.at>, dedekind1 <dedekind1@gmail.com>,
"adrian.hunter" <adrian.hunter@intel.com>,
gregkh <gregkh@linuxfoundation.org>,
"naveen.n.rao" <naveen.n.rao@linux.vnet.ibm.com>,
jpoimboe <jpoimboe@redhat.com>,
Dave Chinner <dchinner@redhat.com>,
"darrick.wong" <darrick.wong@oracle.com>,
"ard.biesheuvel" <ard.biesheuvel@linaro.org>,
George Spelvin <lkml@sdf.org>,
linux-snps-arc <linux-snps-arc@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
ocfs2-devel <ocfs2-devel@oss.oracle.com>,
linux-mtd <linux-mtd@lists.infradead.org>,
sfr <sfr@canb.auug.org.au>
Cc: malat <malat@debian.org>,
"yamada.masahiro" <yamada.masahiro@socionext.com>,
npiggin <npiggin@gmail.com>
Subject: Re: [PATCH v2 2/5] powerpc: module_[32|64].c: replace swap function with built-in one
Date: Mon, 01 Apr 2019 22:08:30 +1100 [thread overview]
Message-ID: <87v9zyoudt.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <14019281554057359@sas1-87f9feb8d943.qloud-c.yandex.net>
Andrey Abramov <st5pub@yandex.ru> writes:
> Replace relaswap with built-in one, because relaswap
> does a simple byte to byte swap.
I replied to v1 with an ack, which stands, this is just a clarification.
> Since Spectre mitigations have made indirect function calls more
> expensive, and the default simple byte copies swap is implemented
> without them, an "optimized" custom swap function is now
> a waste of time as well as code.
Spectre mitigations don't necessarily slow down indirect function calls
on all arches or in all configurations on all arches, so that
justification is a bit dubious.
That's not really a problem for this patch, because the existing
overhead of the function call is probably already enough to rival the
cost of the 24 byte copy.
cheers
______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/
next prev parent reply other threads:[~2019-04-01 11:08 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-31 18:28 [PATCH v2 0/5] simple sort swap function improvements Andrey Abramov
2019-03-31 18:31 ` [PATCH v2 1/5] arch/arc: unwind.c: replace swap function with built-in one Andrey Abramov
2019-04-01 17:53 ` Vineet Gupta
2019-03-31 18:35 ` [PATCH v2 2/5] powerpc: module_[32|64].c: " Andrey Abramov
2019-04-01 11:08 ` Michael Ellerman [this message]
2019-03-31 18:42 ` [PATCH v2 3/5] ocfs2: dir, refcounttree, xattr: replace swap functions " Andrey Abramov
2019-03-31 18:47 ` [PATCH v2 4/5] ubifs: find.c: replace swap function " Andrey Abramov
2019-03-31 18:52 ` [PATCH v2 5/5] Lib: sort.h: replace int size with size_t size in the swap function Andrey Abramov
2019-04-01 9:35 ` Andy Shevchenko
2019-04-01 9:56 ` George Spelvin
2019-04-01 10:28 ` Andy Shevchenko
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=87v9zyoudt.fsf@concordia.ellerman.id.au \
--to=mpe@ellerman.id.au \
--cc=adrian.hunter@intel.com \
--cc=ard.biesheuvel@linaro.org \
--cc=benh@kernel.crashing.org \
--cc=bp@alien8.de \
--cc=darrick.wong@oracle.com \
--cc=dchinner@redhat.com \
--cc=dedekind1@gmail.com \
--cc=gregkh@linuxfoundation.org \
--cc=hpa@zytor.com \
--cc=jlbec@evilplan.org \
--cc=jpoimboe@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mtd@lists.infradead.org \
--cc=linux-snps-arc@lists.infradead.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=lkml@sdf.org \
--cc=malat@debian.org \
--cc=mark@fasheh.com \
--cc=mingo@redhat.com \
--cc=naveen.n.rao@linux.vnet.ibm.com \
--cc=npiggin@gmail.com \
--cc=ocfs2-devel@oss.oracle.com \
--cc=paulus@samba.org \
--cc=richard@nod.at \
--cc=sfr@canb.auug.org.au \
--cc=st5pub@yandex.ru \
--cc=tglx@linutronix.de \
--cc=vgupta@synopsys.com \
--cc=x86@kernel.org \
--cc=yamada.masahiro@socionext.com \
/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