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freebsd/sys/ufs
John Dyson b68a757139 Significant performance improvement for mmap'ed files. This commit
makes MADV_SEQUENTIAL much more effective.  I suggest that
we start using MADV_SEQUENTIAL on system utilities that mmap
their input files, and the I/O is predominantely sequential.
Below is a test with 'cmp' on two relatively large binary files,
where the files are so large that the caching is ineffective:

+ ls -l t1.xxx t2.xxx
-rw-r--r--  1 root  wheel  65598384 Dec 10 12:13 t1.xxx
-rw-r--r--  1 root  wheel  65598384 Dec 10 12:14 t2.xxx

+ time cmp t1.xxx t2.xxx
3.78user 0.70system 1:33.43elapsed 4%CPU

+ time cmpmadv t1.xxx t2.xxx
4.21user 1.05system 0:30.93elapsed 17%CPU

This change is as a result of an observation made by BDE.
1996-12-11 05:17:23 +00:00
..
ffs Submitted by: Archie and me. 1996-11-13 01:45:56 +00:00
lfs Whoops, I should've used the LINT config file. More ts -> tv changes 1996-09-20 05:56:36 +00:00
mfs struct mfsnode bloated in size by 12 bytes, so reduce spare padding by 3 longs. 1996-11-04 20:53:02 +00:00
ufs Significant performance improvement for mmap'ed files. This commit 1996-12-11 05:17:23 +00:00