From: Gabriel de Perthuis <g2p.code-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Rolf Fokkens <rolf-6w2rdlBuEQTpMFipWq+H6g@public.gmane.org>
Cc: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: bcache & btrfs: "Btrfs detected SSD devices, enabling SSD mode"
Date: Fri, 20 Sep 2013 18:25:24 +0200 [thread overview]
Message-ID: <523C76F4.3070809@gmail.com> (raw)
In-Reply-To: <523C71C4.9030606-6w2rdlBuEQTpMFipWq+H6g@public.gmane.org>
> This may be known already, but I noticed the following message in syslog
> during boot:
>
> Btrfs detected SSD devices, enabling SSD mode
>
> Btrfs is right in a sense: there is a SSD involved, but there's a HDD as
> well. I don't think it is an issue, but I have no idea how "btrfs' SSD
> optimizations" will interact with bcache. Might be interesting.
From https://btrfs.wiki.kernel.org/ :
> SSD […] optimizations (e.g. avoiding unnecessary seek optimizations,
sending writes in clusters, even if they are from unrelated files. This
results in larger write operations and faster write throughput)
The optimisations should be beneficial iff bcache is used in writeback
mode. ssd_spread and discard are enabled separately; I'm not sure what
ssd_spread (from the wiki: more strict about finding a large unused
region of the disk for new allocations) would do for bcache.
next prev parent reply other threads:[~2013-09-20 16:25 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-20 16:03 bcache & btrfs: "Btrfs detected SSD devices, enabling SSD mode" Rolf Fokkens
[not found] ` <523C71C4.9030606-6w2rdlBuEQTpMFipWq+H6g@public.gmane.org>
2013-09-20 16:25 ` Gabriel de Perthuis [this message]
[not found] ` <523C76F4.3070809-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2013-09-20 19:25 ` Rolf Fokkens
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