From: Thomas Gleixner <tglx@linutronix.de>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Dan Williams <dan.j.williams@intel.com>,
Arnd Bergmann <arnd@arndb.de>, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Juergen Gross <jgross@suse.com>, X86 ML <x86@kernel.org>,
Toshi Kani <toshi.kani@hp.com>,
linux-nvdimm <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>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Ralf Baechle <ralf@linux-mips.org>,
Henrique de Moraes Holschuh <hmh@hmh.eng.br>,
Michael Ellerman <mpe@ellerman.id.au>, Tejun Heo <tj@kernel.org>,
Paul Mackerras <paulus@samba.org>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v4 6/6] arch, x86: pmem api for ensuring durability of persistent memory updates
Date: Wed, 17 Jun 2015 17:15:57 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.11.1506171714490.4107@nanos> (raw)
In-Reply-To: <CALCETrXXYyjKHi1ajR6aescmjSo5eds=5g_byWpzBRbBNdsgRQ@mail.gmail.com>
On Wed, 17 Jun 2015, Andy Lutomirski wrote:
> On Thu, Jun 11, 2015 at 2:19 PM, Dan Williams <dan.j.williams@intel.com> wrote:
> > +static inline void arch_sync_pmem(void)
> > +{
> > + wmb();
> > + pcommit_sfence();
> > +}
>
> This function is non-intuitive to me. It's really "arch-specific sync
> pmem after one or more copies using arch_memcpy_to_pmem". If normal
> stores or memcpy to non-WC memory is used instead, then it's
> insufficient if the memory is WB and it's unnecessarily slow if the
> memory is WT or UC (the first sfence isn't needed).
>
> I would change the name and add documentation. I'd also add a comment
> about the wmb() being an SFENCE to flush pending non-temporal writes.
Not "I'd also add ...".
Documentation of memory barriers are mandatory.
Thanks,
tglx
WARNING: multiple messages have this Message-ID (diff)
From: Thomas Gleixner <tglx@linutronix.de>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Dan Williams <dan.j.williams@intel.com>,
Arnd Bergmann <arnd@arndb.de>, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Juergen Gross <jgross@suse.com>, X86 ML <x86@kernel.org>,
Toshi Kani <toshi.kani@hp.com>,
linux-nvdimm <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>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Ralf Baechle <ralf@linux-mips.org>,
Henrique de Moraes Holschuh <hmh@hmh.eng.br>,
Michael Ellerman <mpe@ellerman.id.au>, Tejun Heo <tj@kernel.org>,
Paul Mackerras <paulus@samba.org>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v4 6/6] arch, x86: pmem api for ensuring durability of persistent memory updates
Date: Wed, 17 Jun 2015 17:15:57 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.11.1506171714490.4107@nanos> (raw)
In-Reply-To: <CALCETrXXYyjKHi1ajR6aescmjSo5eds=5g_byWpzBRbBNdsgRQ@mail.gmail.com>
On Wed, 17 Jun 2015, Andy Lutomirski wrote:
> On Thu, Jun 11, 2015 at 2:19 PM, Dan Williams <dan.j.williams@intel.com> wrote:
> > +static inline void arch_sync_pmem(void)
> > +{
> > + wmb();
> > + pcommit_sfence();
> > +}
>
> This function is non-intuitive to me. It's really "arch-specific sync
> pmem after one or more copies using arch_memcpy_to_pmem". If normal
> stores or memcpy to non-WC memory is used instead, then it's
> insufficient if the memory is WB and it's unnecessarily slow if the
> memory is WT or UC (the first sfence isn't needed).
>
> I would change the name and add documentation. I'd also add a comment
> about the wmb() being an SFENCE to flush pending non-temporal writes.
Not "I'd also add ...".
Documentation of memory barriers are mandatory.
Thanks,
tglx
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next prev parent reply other threads:[~2015-06-17 15:16 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
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 [this message]
2015-06-17 15:15 ` Thomas Gleixner
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