linux-kernel - Re: [PATCH RFC 01/14] x86/asm: add iosubmit_cmds512() based on movdir64b CPU instruction

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Date:   Thu, 21 Nov 2019 00:26:45 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Luck, Tony" <tony.luck@...el.com>
Cc:     Dave Jiang <dave.jiang@...el.com>, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org, vkoul@...nel.org,
        dan.j.williams@...el.com, jing.lin@...el.com, ashok.raj@...el.com,
        sanjay.k.kumar@...el.com, megha.dey@...el.com,
        jacob.jun.pan@...el.com, yi.l.liu@...el.com, axboe@...nel.dk,
        akpm@...ux-foundation.org, tglx@...utronix.de, mingo@...hat.com,
        fenghua.yu@...el.com, hpa@...or.com
Subject: Re: [PATCH RFC 01/14] x86/asm: add iosubmit_cmds512() based on
 movdir64b CPU instruction

On Wed, Nov 20, 2019 at 03:19:23PM -0800, Luck, Tony wrote:
> That's the underlying functionality of the MOVDIR64B instruction. A
> posted write so no way to know if it succeeded.

So how do you know whether any of the writes went through?

> When using dedicated queues the caller must keep count of how many
> operations are in flight and not send more than the depth of the
> queue.

This way?

-- 
Regards/Gruss,
    Boris.

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