[PATCH 1/4] Add dracut/save-initramfs.sh

Vratislav Podzimek vpodzime at redhat.com
Mon Feb 11 11:52:15 UTC 2013

On Sat, 2013-02-09 at 21:10 -0500, Will Woods wrote:
> Since dracut dropped its slightly-too-clever trick to save a copy of
> itself at /run/initramfs, we need to locate or save a copy of initramfs
> so we can switch back into it and shut down properly.
> So: first, check to see if we're running off media; if so, we can just
> use the initramfs from the media. Easy!
> Otherwise we need to save a copy. The anaconda initramfs (for current
> F18-ish images on x86_64) uses about 96M RAM when unpacked, which is a
> bit wasteful.
> To save RAM we can filter out some stuff we don't need for shutdown:
> * kernel modules: ~39M
> * firmware:        ~9M
> * python:          ~8M
> * ssl certs:       ~1M
> * fsck binaries:   ~1M
> which leaves us with 38M of data. We can reduce this to 18M by gzipping
> it, but that delays startup for 3s on my test system.
> (Using xz would save 4.5M, but it takes 15s (!) and uses 100M RAM (!!).)
> Using gzip -1 drops this to just over 1 second; RAM use goes up by 1M,
> but that seems like a reasonable tradeoff.
> If `pigz` is available, that gets used instead, which makes the delay
> basically negligible on any modern multicore system.
These all look good to me.

Vratislav Podzimek

Anaconda Rider | Red Hat, Inc. | Brno - Czech Republic

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