From: Martin Steigerwald <martin@lichtvoll.de>
To: Andreas Mohr <andi@lisas.de>
Cc: Jeff Chua <jeff.chua.linux@gmail.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org, Christoph Hellwig <hch@lst.de>
Subject: Re: Stop SSD from waiting for "Spinning up disk..."
Date: Tue, 23 Jun 2015 20:55:49 +0200
Message-ID: <3819569.ix7n6b03GW@merkaba>
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Am Dienstag, 23. Juni 2015, 20:26:12 schriebst Du:
> Hi,

Hi,

> [proper In-Reply-To trail missing since lkml.org now fails to provide it]
[…]
> > Greg,
> > 
> > SSD is coming mainstream and it doesn't make sense wasting time
> > spinning up "disk" ...
> 
> ...which probably is not truly being achieved
> by providing a *custom* kernel parameter
> which does apply to only those disk instances
> which some users *specifically* care about.
> 
> Some things come to mind:
> 
> - at this scope, generally spoken
>   one shouldn't be concerned with whether "we are SSD",
>   but rather whether "we (do not) need spinup"
>   (which might apply to a ton of different SCSI-based storage devices,
>   even some SAN-based platter-based ones)
>   *This* is what this is about
>   (and this could then have been reflected in kernel parameter naming)
[…]
> - the kernel must already have some mechanisms to discern between
> (non-)platters (e.g. perhaps for knowing whether to support SSD TRIM
> command)

Yep, for the first SSD in this laptop:

merkaba:/sys> cat 
./devices/pci0000:00/0000:00:1f.2/ata2/host1/target1:0:0/1:0:0:0/block/sda/queue/rotational
0

[…]

Thanks,
-- 
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA  B82F 991B EAAC A599 84C7
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