On Thu, 2003-10-23 at 01:55, Joakim Tjernlund wrote:

I did a kernel profile(included below) of the bootup of my custom MPC862 board and I
noticed that __restore_flags gets a very high count. I am suprised that such a small
assembler routine gets such a high count. __cli, _save_flags_ptr and __sti are much lower.
A small test program with a tight select loop on fds 0,1 or 2 also makes __restore_flags
go wild.
Anyone know why?

Simple: when interrupts are off (typically after a __save_flags),
there can't be any profiling interrupts.  As soon as you restore
the interrupts (_restore_flags), the interrupt used for profiling
will fire.

--
Gary Thomas [off-list ref]
MLB Associates


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