Jeff King wrote:
> OK, that's horrific. For me, the stat information for linux-2.6 all sits
> in cache and it takes about 0.3 seconds to refresh the index. I have 8G
> of ram and a nice SSD, though it doesn't actually hit the disk at all.
>
> Is it really faulting the stat information from disk that takes so long?
> Have you tried running "perf" on "git update-index --refresh"?
Cold cache:
Performance counter stats for 'git update-index --refresh':
9725.574501 task-clock-msecs # 0.337 CPUs
58,163 context-switches # 0.006 M/sec
94 CPU-migrations # 0.000 M/sec
8,637 page-faults # 0.001 M/sec
12,825,956,531 cycles # 1318.787 M/sec (scaled from 33.43%)
2,696,089,912 instructions # 0.210 IPC (scaled from 50.03%)
457,705,110 branches # 47.062 M/sec (scaled from 51.30%)
40,033,685 branch-misses # 8.747 % (scaled from 50.19%)
149,071,234 cache-references # 15.328 M/sec (scaled from 32.83%)
9,662,661 cache-misses # 0.994 M/sec (scaled from 32.27%)
28.846625099 seconds time elapsed
Warm cache is 0.88 seconds, but cold cache is typical; I use a cheap netbook
for a lot of different stuff.
Also, I can get much worse cold cache numbers on eg, a fairly average
VPS node, where it takes > 1 minute.
--
see shy jo
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