linux-bcachefs.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Kuan-Wei Chiu <visitorckw@gmail.com>
To: Kent Overstreet <kent.overstreet@linux.dev>
Cc: colyli@suse.de, bfoster@redhat.com, jserv@ccns.ncku.edu.tw,
	linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-bcachefs@vger.kernel.org
Subject: Re: [PATCH 2/5] bcachefs: Introduce parent function for sort_cmp_size()
Date: Mon, 22 Jan 2024 01:05:28 +0800	[thread overview]
Message-ID: <Za1O2JDOnTRL0QvL@visitorckw-System-Product-Name> (raw)
In-Reply-To: <vrzgjxym2gnawuds54s4lr4zqbldm6sxp5yksrz5467hcrzjtp@lphbsqbidqdm>

On Sun, Jan 21, 2024 at 11:17:30AM -0500, Kent Overstreet wrote:
> On Sun, Jan 21, 2024 at 11:36:46PM +0800, Kuan-Wei Chiu wrote:
> > When dealing with array indices, the parent's index can be obtained
> > using the formula (i - 1) / 2. However, when working with byte offsets,
> > this approach is not straightforward. To address this, we have
> > introduced a branch-free parent function that does not require any
> > division operations to calculate the parent's byte offset.
> 
> This is a good commit message - but it would be even better if it was a
> function comment on parent()
>
Sure, however, it seems that sort_cmp_size() can be directly replaced
with the sort function from include/linux. Once we decide on the
cleanup tasks, if we still choose to retain this patch, I will make the
adjustments.
> > 
> > Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
> > ---
> > This patch has undergone unit testing using the following code [1].
> > 
> > [1]:
> > static int test(void)
> > {
> >     size_t i, p, size, lsbit;
> > 
> >     for (i = 0; i < 10000; i++) {
> >         size = get_random_u32() % (1U << 10);
> >         lsbit = size & -size;
> >         i = get_random_u32() % (1U << 20) * size + size;
> >         p = parent(i, lsbit, size);
> >         if (p != (i / size - 1) / 2 * size)
> >             return -1;
> >     }
> > 
> >     return 0;
> > }
> > 
> >  fs/bcachefs/util.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > diff --git a/fs/bcachefs/util.c b/fs/bcachefs/util.c
> > index bbc83b43162e..f5bbf96df2ce 100644
> > --- a/fs/bcachefs/util.c
> > +++ b/fs/bcachefs/util.c
> > @@ -907,6 +907,13 @@ static inline void do_swap(void *base, size_t n, size_t size,
> >  		  size);
> >  }
> >  
> > +static inline size_t parent(size_t i, size_t lsbit, size_t size)
> > +{
> > +	i -= size;
> > +	i -= size & -(i & lsbit);
> > +	return i >> 1;
> > +}
> > +
> >  void eytzinger0_sort(void *base, size_t n, size_t size,
> >  		     int (*cmp_func)(const void *, const void *, size_t),
> >  		     void (*swap_func)(void *, void *, size_t))
> > -- 
> > 2.25.1
> > 

  reply	other threads:[~2024-01-21 17:05 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-21 15:36 [PATCH 0/5] Optimize number of comparisons for heap/heapsort implementaion Kuan-Wei Chiu
2024-01-21 15:36 ` [PATCH 1/5] bcachefs: Optimize eytzinger0_sort() using bottom-up heapsort Kuan-Wei Chiu
2024-01-21 15:36 ` [PATCH 2/5] bcachefs: Introduce parent function for sort_cmp_size() Kuan-Wei Chiu
2024-01-21 16:17   ` Kent Overstreet
2024-01-21 17:05     ` Kuan-Wei Chiu [this message]
2024-01-21 17:37       ` Kent Overstreet
2024-01-21 15:36 ` [PATCH 3/5] bcachefs: Optimize sort_cmp_size() using bottom-up heapsort Kuan-Wei Chiu
2024-01-21 15:36 ` [PATCH 4/5] bcachefs: Optimize number of comparisons in heap_sift_down Kuan-Wei Chiu
2024-01-21 15:36 ` [PATCH 5/5] bcache: Optimize number of comparisons in heap_sift Kuan-Wei Chiu
2024-01-21 16:21 ` [PATCH 0/5] Optimize number of comparisons for heap/heapsort implementaion Kent Overstreet
2024-01-21 16:55   ` Kuan-Wei Chiu
2024-01-21 17:41     ` Kent Overstreet
2024-01-22 15:06       ` Kuan-Wei Chiu
2024-01-22 16:06         ` Kent Overstreet
2024-01-22 16:23           ` Kuan-Wei Chiu

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=Za1O2JDOnTRL0QvL@visitorckw-System-Product-Name \
    --to=visitorckw@gmail.com \
    --cc=bfoster@redhat.com \
    --cc=colyli@suse.de \
    --cc=jserv@ccns.ncku.edu.tw \
    --cc=kent.overstreet@linux.dev \
    --cc=linux-bcache@vger.kernel.org \
    --cc=linux-bcachefs@vger.kernel.org \
    --cc=linux-kernel@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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).