Re: Add "--dirstat" for some directory statistics

From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Feb 11, 2008, 21:17 UTC
Message-ID: <alpine.LFD.1.00.0802111302470.2920@woody.linux-foundation.org>
In-Reply-To: <alpine.LFD.1.00.0802111230200.2920@woody.linux-foundation.org>

On Mon, 11 Feb 2008, Linus Torvalds wrote:

> 
> The reporting limit has been arbitrarily set at 3%, which seems to be a 
> pretty good cut-off, but I made it an option variable in case anybody 
> would ever want to make it a dynamic cutoff.

Side note: that 3% isn't actually _too_ arbitrary. I did actually test things a bit.

So it seems to be a good limit that ensures that you'll basically never see more than one page worth of reporting (if you did, it wouldn't be a very good summary). So in theory, if something is _just_ right and really balanced out across a wide variety of directories, you can get 33 lines of output, but in practice it's unusual to get more than 10-15 entries.

In the kernel, the most spread out commit I've found so far is 18 entries:

    CONFIG_HIGHPTE vs. sub-page page tables.

   3% arch/powerpc/mm/
   5% arch/sparc/mm/
   6% arch/
   5% include/asm-alpha/
   3% include/asm-avr32/
   3% include/asm-cris/
   4% include/asm-ia64/
   6% include/asm-m68k/
   3% include/asm-mips/
   7% include/asm-powerpc/
   6% include/asm-sh/
   4% include/asm-sparc64/
   3% include/asm-um/
   6% include/asm-x86/
   3% include/asm-xtensa/
   3% include/linux/
  14% include/
   7% mm/
 53 files changed, 326 insertions(+), 132 deletions(-)

but it's not like I looked through all of them (and I'm sure you can get more if you select just the right commit range to generate the diff).

The point being that a 4-percent cut-off would likely be so big that it would have hidden the details in the above example.

A 2% cut-off is worth trying, though. It does get a bit more detail, and the likelihood of it actually causing a 50-line report is probably vanishingly small, so it might be worth playing around with. The above 18-entry example grows to 23 entries with a 2% limit, which is very borderline on a traditional 80x24 terminal, but still just barely "one page" which was my personal rule to aim for.

			Linus