All of lore.kernel.org
 help / color / mirror / Atom feed
From: Neal Gompa <ngompa13@gmail.com>
To: David Sterba <dsterba@suse.cz>, Neal Gompa <ngompa13@gmail.com>,
	David Sterba <dsterba@suse.com>,
	Btrfs BTRFS <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH 0/6] Remove highmem allocations, kmap/kunmap
Date: Thu, 8 Jul 2021 18:24:16 -0400	[thread overview]
Message-ID: <CAEg-Je8FJwM6REQPqpyYGES_sCgv4fWY7X7pW5XABAVBvsPjxg@mail.gmail.com> (raw)
In-Reply-To: <20210708124959.GZ2610@suse.cz>

On Thu, Jul 8, 2021 at 8:52 AM David Sterba <dsterba@suse.cz> wrote:
>
> On Thu, Jul 08, 2021 at 08:45:12AM -0400, Neal Gompa wrote:
> > On Thu, Jul 8, 2021 at 7:48 AM David Sterba <dsterba@suse.com> wrote:
> > >
> > > The highmem was maybe was a good idea long time ago but with 64bit
> > > architectures everywhere I don't think we need to take it into account.
> > > This does not mean this 32bit won't work, just that it won't try to use
> > > temporary pages in highmem for compression and raid56. The key word is
> > > temporary. Combining a very fast device (like hundreds of megabytes
> > > throughput) and 32bit machine with reasonable memory (for 32bit, like
> > > 8G), it could become a problem once low memory is scarce.
> > >
> > > David Sterba (6):
> > >   btrfs: drop from __GFP_HIGHMEM all allocations
> > >   btrfs: compression: drop kmap/kunmap from lzo
> > >   btrfs: compression: drop kmap/kunmap from zlib
> > >   btrfs: compression: drop kmap/kunmap from zstd
> > >   btrfs: compression: drop kmap/kunmap from generic helpers
> > >   btrfs: check-integrity: drop kmap/kunmap for block pages
> > >
> > >  fs/btrfs/check-integrity.c | 11 +++-------
> > >  fs/btrfs/compression.c     |  6 ++----
> > >  fs/btrfs/inode.c           |  3 +--
> > >  fs/btrfs/lzo.c             | 42 +++++++++++---------------------------
> > >  fs/btrfs/raid56.c          | 10 ++++-----
> > >  fs/btrfs/zlib.c            | 42 +++++++++++++-------------------------
> > >  fs/btrfs/zstd.c            | 33 +++++++++++-------------------
> > >  7 files changed, 49 insertions(+), 98 deletions(-)
> > >
> >
> > I'd be concerned about the impact of this on SBC devices. All Fedora
> > ARM images have zstd compression applied to them, and it would suck if
> > we had a performance regression here because of this.
>
> How much memory do the SBC devices have?

On average? Probably between 1 to 4 GB of RAM. Usually 2GB of RAM is common.


-- 
真実はいつも一つ！/ Always, there's only one truth!

  reply	other threads:[~2021-07-08 22:24 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-08 11:45 [PATCH 0/6] Remove highmem allocations, kmap/kunmap David Sterba
2021-07-08 11:45 ` [PATCH 1/6] btrfs: drop from __GFP_HIGHMEM all allocations David Sterba
2021-07-08 11:45 ` [PATCH 2/6] btrfs: compression: drop kmap/kunmap from lzo David Sterba
2021-07-08 11:45 ` [PATCH 3/6] btrfs: compression: drop kmap/kunmap from zlib David Sterba
2021-07-08 11:45 ` [PATCH 4/6] btrfs: compression: drop kmap/kunmap from zstd David Sterba
2021-07-08 11:45 ` [PATCH 5/6] btrfs: compression: drop kmap/kunmap from generic helpers David Sterba
2021-07-08 11:45 ` [PATCH 6/6] btrfs: check-integrity: drop kmap/kunmap for block pages David Sterba
2021-07-08 12:45 ` [PATCH 0/6] Remove highmem allocations, kmap/kunmap Neal Gompa
2021-07-08 12:49   ` David Sterba
2021-07-08 22:24     ` Neal Gompa [this message]
2021-07-08 23:53   ` Qu Wenruo
2021-07-09  6:46     ` Christoph Hellwig
2021-07-09  7:12       ` Qu Wenruo
2021-07-09 12:15         ` Neal Gompa
2021-07-10  9:50           ` Qu Wenruo
2021-07-10 11:15             ` Christoph Hellwig
2021-07-10 11:37               ` Qu Wenruo

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=CAEg-Je8FJwM6REQPqpyYGES_sCgv4fWY7X7pW5XABAVBvsPjxg@mail.gmail.com \
    --to=ngompa13@gmail.com \
    --cc=dsterba@suse.com \
    --cc=dsterba@suse.cz \
    --cc=linux-btrfs@vger.kernel.org \
    /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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.