The patch and a list of all functions which owned the lock for more then
1.5 milliseconds is at
http://www.colorfullife.com/manfreds/kernel_lock/
OTHO, 2048 cpu cycles is about as long as __cpu_user() needs for 700
bytes if source,dest are currently not in the cache (I've tested it
with a 16 MB move from user mode). The memmove will be even
slower with faster CPU's (i.e. with a higher cpu clock/bus clock
multiplier)
My question:
Shouldn't we change file_read_actor() [mm/filemap.c, the function which
copies data from the page cache to user mode]:
we could release the kernel lock if we copy more than 1024 bytes.
(we currently do that only if the user mode memory is not paged in.)
Manfred
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