From: Dan Williams <dan.j.williams@intel.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Arnd Bergmann <arnd@arndb.de>, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Juergen Gross <jgross@suse.com>, X86 ML <x86@kernel.org>,
"Kani, Toshimitsu" <toshi.kani@hp.com>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@ml01.01.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Luis Rodriguez <mcgrof@suse.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Stefan Bader <stefan.bader@canonical.com>,
Andy Lutomirski <luto@amacapital.net>,
linux-mm@kvack.org, Geert Uytterhoeven <geert@linux-m68k.org>,
Ralf Baechle <ralf@linux-mips.org>,
Henrique de Moraes Holschuh <hmh@hmh.eng.br>,
mpe@ellerman.id.au, Tejun Heo <tj@kernel.org>,
Paul Mackerras <paulus@samba.org>
Subject: Re: [PATCH v4 6/6] arch, x86: pmem api for ensuring durability of persistent memory updates
Date: Wed, 17 Jun 2015 07:54:14 -0700 [thread overview]
Message-ID: <CAPcyv4hkS+3iTqJkcuES13vZKNYdWKufAqjD3+Pf4BaZ88nZEQ@mail.gmail.com> (raw)
In-Reply-To: <20150617113121.GC9246@lst.de>
On Wed, Jun 17, 2015 at 4:31 AM, Christoph Hellwig <hch@lst.de> wrote:
> This mess with arch_ methods and an ops vecor is almost unreadable.
>
> What's the problem with having something like:
>
> pmem_foo()
> {
> if (arch_has_pmem) // or sync_pmem
> arch_pmem_foo();
> generic_pmem_foo();
> }
>
> This adds a branch at runtime, but that shoudn't really be any slower
> than an indirect call on architectures that matter.
No doubt it's premature optimization, but it bothered me that we'll
end up calling cpuid perhaps multiple times every i/o. If it's just a
readability concern I could wrap it in helpers. Getting it upstream
is my primary concern at this point so I have no strong attachment to
the indirect calls if that's all that is preventing an ack.
WARNING: multiple messages have this Message-ID (diff)
From: Dan Williams <dan.j.williams@intel.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Arnd Bergmann <arnd@arndb.de>, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Juergen Gross <jgross@suse.com>, X86 ML <x86@kernel.org>,
"Kani, Toshimitsu" <toshi.kani@hp.com>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Luis Rodriguez <mcgrof@suse.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Stefan Bader <stefan.bader@canonical.com>,
Andy Lutomirski <luto@amacapital.net>,
linux-mm@kvack.org, Geert Uytterhoeven <geert@linux-m68k.org>,
Ralf Baechle <ralf@linux-mips.org>,
Henrique de Moraes Holschuh <hmh@hmh.eng.br>,
mpe@ellerman.id.au, Tejun Heo <tj@kernel.org>,
Paul Mackerras <paulus@samba.org>
Subject: Re: [PATCH v4 6/6] arch, x86: pmem api for ensuring durability of persistent memory updates
Date: Wed, 17 Jun 2015 07:54:14 -0700 [thread overview]
Message-ID: <CAPcyv4hkS+3iTqJkcuES13vZKNYdWKufAqjD3+Pf4BaZ88nZEQ@mail.gmail.com> (raw)
In-Reply-To: <20150617113121.GC9246@lst.de>
On Wed, Jun 17, 2015 at 4:31 AM, Christoph Hellwig <hch@lst.de> wrote:
> This mess with arch_ methods and an ops vecor is almost unreadable.
>
> What's the problem with having something like:
>
> pmem_foo()
> {
> if (arch_has_pmem) // or sync_pmem
> arch_pmem_foo();
> generic_pmem_foo();
> }
>
> This adds a branch at runtime, but that shoudn't really be any slower
> than an indirect call on architectures that matter.
No doubt it's premature optimization, but it bothered me that we'll
end up calling cpuid perhaps multiple times every i/o. If it's just a
readability concern I could wrap it in helpers. Getting it upstream
is my primary concern at this point so I have no strong attachment to
the indirect calls if that's all that is preventing an ack.
--
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next prev parent reply other threads:[~2015-06-17 14:54 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-11 21:19 [-tip PATCH v4 0/6] pmem api, generic ioremap_cache, and memremap Dan Williams
2015-06-11 21:19 ` Dan Williams
2015-06-11 21:19 ` [PATCH v4 1/6] arch: unify ioremap prototypes and macro aliases Dan Williams
2015-06-11 21:19 ` Dan Williams
2015-06-17 11:14 ` Christoph Hellwig
2015-06-17 11:14 ` Christoph Hellwig
2015-06-17 17:35 ` Toshi Kani
2015-06-17 17:35 ` Toshi Kani
2015-06-11 21:19 ` [PATCH v4 2/6] cleanup IORESOURCE_CACHEABLE vs ioremap() Dan Williams
2015-06-11 21:19 ` Dan Williams
2015-06-11 21:19 ` [PATCH v4 3/6] arch/*/asm/io.h: add ioremap_cache() to all architectures Dan Williams
2015-06-11 21:19 ` Dan Williams
2015-06-17 11:27 ` Christoph Hellwig
2015-06-17 11:27 ` Christoph Hellwig
2015-06-11 21:19 ` [PATCH v4 4/6] devm: fix ioremap_cache() usage Dan Williams
2015-06-11 21:19 ` Dan Williams
2015-06-11 21:19 ` [PATCH v4 5/6] arch: introduce memremap_cache() and memremap_wt() Dan Williams
2015-06-11 21:19 ` Dan Williams
2015-06-19 21:28 ` Toshi Kani
2015-06-19 21:28 ` Toshi Kani
2015-06-11 21:19 ` [PATCH v4 6/6] arch, x86: pmem api for ensuring durability of persistent memory updates Dan Williams
2015-06-11 21:19 ` Dan Williams
2015-06-17 11:31 ` Christoph Hellwig
2015-06-17 11:31 ` Christoph Hellwig
2015-06-17 14:54 ` Dan Williams [this message]
2015-06-17 14:54 ` Dan Williams
2015-06-17 15:08 ` Andy Lutomirski
2015-06-17 15:08 ` Andy Lutomirski
2015-06-17 15:07 ` Andy Lutomirski
2015-06-17 15:07 ` Andy Lutomirski
2015-06-17 15:15 ` Thomas Gleixner
2015-06-17 15:15 ` Thomas Gleixner
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