linux-kernel - Re: [PATCH 1/2] nvme: Wait at least 6000ms before entering the deepest idle state

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Date:   Sat, 27 May 2017 09:14:09 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     Christoph Hellwig <hch@....de>, Jens Axboe <axboe@...nel.dk>,
        Sagi Grimberg <sagi@...mberg.me>,
        Keith Busch <keith.busch@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        linux-nvme <linux-nvme@...ts.infradead.org>
Subject: Re: [PATCH 1/2] nvme: Wait at least 6000ms before entering the
 deepest idle state

On Sat, May 27, 2017 at 9:08 AM, Andy Lutomirski <luto@...nel.org> wrote:
> On Fri, May 26, 2017 at 1:52 AM, Christoph Hellwig <hch@....de> wrote:
>>
>> Just following a somewhat odd and arbitray policy from another driver
>> that doesn't fix anything by itself certainly isn't stable material.
>
> I'd be fine with skipping this patch entirely at least until we find
> some evidence that it solves a problem instead.

It's certainly worth waiting for confirmation that it actually changes
anything, but I did want to pipe up to say that "following a somewhat
odd and arbitrary policy from another driver" is not wrong per se.

In fact, on the power management we pretty much had to do that, simply
because that "odd and arbitrary policy" (Windows behavior) was the
only thing that had ever been tested by anybody. Same goes for a lot
of PCI subsystem behavior etc.

So it's not wrong per se to just emulate others' behaviors. But yes,
we should have some reason for doing so, not just doing so blindly.

           Linus