Re: [Census] So who uses git?

On 2/1/06, Linus Torvalds [off-list ref] wrote:

quoted

$ time git update-index --refresh

real    0m21.500s
user    0m0.358s
sys     0m1.406s

WinNT, NTFS, 13k files, hot cache.

That's 25% less files than the Linux kernel, and I can do that operation
in 0m0.062s (0.012s user, 0.048s system).

correction. It's 18k files, which is almost the same as 2.6.13-rc6. But these
files got *very* long names (the project poisoned by classical C++ education
and breaks windows' 255 chars limit on filename length from time to time).
Refresh index in 2.6.13 is actualy consistantly faster:

$ cd src/linux-2.6.13-rc6
$ time git update-index --refresh
real    0m1.344s
user    0m0.358s
sys     0m0.984s

So WinNT/cygwin is about 2.5 _orders_of_maginitude_ slower here, or 340
times slower.

Now, I'm tempted to say that NT is a piece of sh*t, but the fact is, your
CPU-times seem to indicate that most of it is IO (and the "real" cost is
just 1.7 seconds, much of which is system time, which in turn itself is
probably due to the IO costs too - so even that isn't comparable with
the ).

Which may mean that you simply don't have enough memory to cache the whole
thing. Which may be NT sucking, of course ("we don't like to use more than
10% of memory for caches"), but it might also be a tunable (which is sucky
in itself, of course), but finally, it might just be that you just don't
have a ton of memory. I've got 2GB in my machines, although 1GB is plenty
to cache the kernel.

I have 2Gb, the "System Cache" is around 1.5Gb, and this is PIV 3.2GHz.
There seem to be no tunables for any kind of system stuff
(savin' on support costs, do they?).
You'd be very hardpressed not to say that windows is a piece of sh*t.

The "benchmark: several times in a row:

$ time git update-index --refresh
real    0m1.766s
user    0m0.498s
sys     0m1.203s

$ time git update-index --refresh
real    0m1.766s
user    0m0.358s
sys     0m1.390s

$ time git update-index --refresh
real    0m1.781s
user    0m0.420s
sys     0m1.311s

$ time git update-index --refresh
real    0m1.875s
user    0m0.374s
sys     0m1.343s

$ time git update-index --refresh
real    0m1.766s
user    0m0.326s
sys     0m1.375s

It is always almost the same time. I don't think it's IO, looks more like
cache accesses. It is just that bad in this cygwin+win2k combination.
Besides, I don't trust "time <command>" on windows much: it returned
sys time 0 for git-update-index in a directory which was read before.
Yes, there was disk activity, I can hear it real good with that barrakuda.