Align the offset in vn_rdwr_inchunks() so that at most the first and

the last chunk are misaligned relative to a MAXBSIZE byte boundary.
vn_rdwr_inchunks() is used mainly for elf core dumps, and elf sections
are usually perfectly misaligned relative to MAXBSIZE, and chunking
prevents the file system from doing much realigning.

This gives a surprisingly large speedup for core dumps -- from 50 to
13 seconds for a 512MB core dump here.  The pessimization was mostly
from an interaction of the misalignment with IO_DIRECT.  It increased
the number of i/o's for each chunk by a factor of 5 (3 writes and 2
read-before-writes instead of 1 write).

0 files changed, 0 insertions, 0 deletions