Re: Extremely slooooow __sys_ftruncate?

"truncate" may be synchronous on FreeBSD - almost nothing is on Linux.

-Kip

On Thu, Mar 20, 2008 at 8:02 PM, Steve Kargl
<sgk@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
In the process of helping to debug a problem with gcc-4.4.0
(actually a gfortran problem), I run gprof on the executable.
The profile shows that __sys_ftruncate is extremely slow.

% cumulative self self total
time seconds seconds calls ms/call ms/call name
85.6 6.05 6.05 51830 0.12 0.12 __sys_ftruncate [2]
5.6 6.44 0.40 0 100.00% .mcount (101)
1.7 6.56 0.12 51872 0.00 0.00 _lseek [5]
1.6 6.67 0.11 52055 0.00 0.00 sigprocmask [6]
0.8 6.73 0.06 103687 0.00 0.00 memset [14]
0.4 6.76 0.03 488 0.06 0.06 __sys_write [18]
0.4 6.79 0.03 0 100.00% formatted_transfer_scalar

time ./z
184.21 real 0.98 user 6.57 sys

This program should finish well under 184 seconds. The same program
and exact same gcc/gfortran source on linux shows
real 0m0.555s user 0m0.103s sys 0m0.452s

Is __sys_ftruncate known to have performance problems?

--
Steve
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