From: Borislav Petkov <bp@alien8.de>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>,
"dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"vkoul@kernel.org" <vkoul@kernel.org>,
"Luck, Tony" <tony.luck@intel.com>,
"Lin, Jing" <jing.lin@intel.com>,
"Raj, Ashok" <ashok.raj@intel.com>,
"Kumar, Sanjay K" <sanjay.k.kumar@intel.com>,
"Dey, Megha" <megha.dey@intel.com>,
"Pan, Jacob jun" <jacob.jun.pan@intel.com>,
"Liu, Yi L" <yi.l.liu@intel.com>,
"axboe@kernel.dk" <axboe@kernel.dk>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"Yu, Fenghua" <fenghua.yu@intel.com>,
"hpa@zytor.com" <hpa@zytor.com>
Subject: Re: [PATCH RFC 01/14] x86/asm: add iosubmit_cmds512() based on movdir64b CPU instruction
Date: Fri, 22 Nov 2019 19:44:35 +0100 [thread overview]
Message-ID: <20191122184435.GK6289@zn.tnic> (raw)
In-Reply-To: <CAPcyv4isyT3FOPARBc8cSANbRWjhAsJrZTkT-fYivPZZJzF=tw@mail.gmail.com>
On Fri, Nov 22, 2019 at 09:20:39AM -0800, Dan Williams wrote:
> For those cases the thought would be to have memset512() for case1 and
> __iowrite512_copy() for case3. Where memset512() writes a
> non-incrementing source to an incrementing destination, and
> __iowrite512_copy() copies an incrementing source to an incrementing
> destination. Those 2 helpers *would* have fallbacks, but with the
> option to use something like cpu_has_write512() to check in advance
> whether those routines will fallback, or not.
>
> That can be a discussion for a future patchset when those users arrive.
Oh, sure, of course.
My only angle is very simple: if the MOVDIR* et al is only supported on
upcoming Intel platforms and looking at the use cases:
1. clear poison/MKTME
3. copy iomem in big chunks
I'm going to venture a guess that those two cases are going to be
happening only on Intel platforms which already support MODVIR*. So
wouldn't really need to do any generic helpers because those use cases
are very specific already. Which would make your feature detection a
one-time, driver-init time thing anyway...
Unless I misunderstand those cases and there really is a use case
where the thing would fallback and the fallback would really be for an
"unenlightened" platform without that MOVDIR* hw support...?
Hmmm.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2019-11-22 18:44 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-20 21:23 [PATCH RFC 00/14] idxd driver for Intel Data Streaming Accelerator Dave Jiang
2019-11-20 21:23 ` [PATCH RFC 01/14] x86/asm: add iosubmit_cmds512() based on movdir64b CPU instruction Dave Jiang
2019-11-20 21:50 ` Dave Hansen
2019-11-20 23:46 ` Dave Jiang
2019-11-20 21:53 ` Borislav Petkov
2019-11-20 23:19 ` Luck, Tony
2019-11-20 23:26 ` Borislav Petkov
2019-11-21 0:15 ` Luck, Tony
2019-11-21 0:27 ` Dan Williams
2019-11-21 0:53 ` Thomas Gleixner
2019-11-21 1:32 ` Dan Williams
2019-11-21 10:37 ` Borislav Petkov
2019-11-21 0:21 ` Dan Williams
2019-11-21 0:22 ` Thomas Gleixner
2019-11-21 0:27 ` Dave Jiang
2019-11-21 0:10 ` Dave Jiang
2019-11-21 10:59 ` Borislav Petkov
2019-11-21 16:52 ` Dave Jiang
2019-11-22 8:59 ` Borislav Petkov
2019-11-22 17:20 ` Dan Williams
2019-11-22 18:44 ` Borislav Petkov [this message]
2019-11-22 18:50 ` Dan Williams
2019-11-20 21:23 ` [PATCH RFC 02/14] dmaengine: break out channel registration Dave Jiang
2019-11-20 21:24 ` [PATCH RFC 03/14] dmaengine: add new dma device registration Dave Jiang
2019-11-20 21:24 ` [PATCH RFC 04/14] mm: create common code from request allocation based from blk-mq code Dave Jiang
2019-11-20 21:24 ` [PATCH RFC 05/14] dmaengine: add dma_request support functions Dave Jiang
2019-11-20 21:24 ` [PATCH RFC 06/14] dmaengine: add dma request submit and completion path support Dave Jiang
2019-11-20 21:24 ` [PATCH RFC 07/14] dmaengine: update dmatest to support dma request Dave Jiang
2019-11-20 21:24 ` [PATCH RFC 08/14] dmaengine: idxd: Init and probe for Intel data accelerators Dave Jiang
2019-11-20 21:24 ` [PATCH RFC 09/14] dmaengine: idxd: add configuration component of driver Dave Jiang
2019-11-20 21:24 ` [PATCH RFC 10/14] dmaengine: idxd: add descriptor manipulation routines Dave Jiang
2019-11-20 21:24 ` [PATCH RFC 11/14] dmaengine: idxd: connect idxd to dmaengine subsystem Dave Jiang
2019-11-20 21:24 ` [PATCH RFC 12/14] dmaengine: request submit optimization Dave Jiang
2019-11-20 21:25 ` [PATCH RFC 13/14] dmaengine: idxd: add char driver to expose submission portal to userland Dave Jiang
2019-11-20 21:25 ` [PATCH RFC 14/14] dmaengine: idxd: add sysfs ABI for idxd driver Dave Jiang
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