Kexec Archive on lore.kernel.org
 help / color / mirror / Atom feed
From: Simon Horman <horms@verge.net.au>
To: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Cc: kexec@lists.infradead.org, stefan.roscher@de.ibm.com
Subject: Re: [PATCH] kexec: use mmap instead of read for slurp_file()
Date: Mon, 7 Sep 2015 15:44:57 +0900	[thread overview]
Message-ID: <20150907064457.GA12433@verge.net.au> (raw)
In-Reply-To: <20150904141159.182c2f08@holzheu>

On Fri, Sep 04, 2015 at 02:11:59PM +0200, Michael Holzheu wrote:
> The slurp_fd() function allocates memory and uses the read() system call.
> This results in double memory consumption for image and initrd:
> 
>  1) Memory allocated in user space by the kexec tool
>  2) Memory allocated in kernel by the kexec() system call
> 
> Therefore use mmap() for non-character devices to reduce the runtime
> memory consumption of the kexec tool.
> 
> The following use case illustrates the usefulness of this patch a bit more:
> 
>  1) Boot a 4 GB Linux system
>  2) Read kernel and 1,5 GB ramdisk from external source into local tmpfs (ram)
>  3) kexec the kernel and ramdisk
> 
>  Without this patch for the kexec runtime we need:
> 
>  1,5 GB (tmpfs) + 1,5 GB (kexec malloc) + 1,5 GB (kernel memory) = 4,5 GB
> 
> Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>

Thanks, applied.

_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

  reply	other threads:[~2015-09-07  6:45 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-08-18 16:17 [RFC PATCH] kexec: use mmap instead of read for slurp_file() Michael Holzheu
2015-08-28 14:26 ` PING: " Michael Holzheu
2015-09-02  1:07 ` Simon Horman
2015-09-02  8:48   ` Michael Holzheu
2015-09-04  9:45     ` Simon Horman
2015-09-04 12:11       ` [PATCH] " Michael Holzheu
2015-09-07  6:44         ` Simon Horman [this message]
2015-10-15  0:05         ` Geoff Levand
2015-10-15 12:31           ` Michael Holzheu

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20150907064457.GA12433@verge.net.au \
    --to=horms@verge.net.au \
    --cc=holzheu@linux.vnet.ibm.com \
    --cc=kexec@lists.infradead.org \
    --cc=stefan.roscher@de.ibm.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox