CVS commit: src/sys/uvm

["Jaromir Dolecek" <jdolecek%netbsd.org@localhost>]

Module Name:    src
Committed By:   jdolecek
Date:           Sat May 19 15:13:26 UTC 2018

Modified Files:
        src/sys/uvm: uvm_bio.c

Log Message:
change code to take advantage of direct map when available, avoiding the need
to map pages into kernel

this improves performance of UBC-based (read(2)/write(2)) I/O especially
for cached block I/O - sequential read on my NVMe goes from 1.7 GB/s to 1.9 GB/s
for non-cached, and from 2.2 GB/s to 5.6 GB/s for cached read

the new code is conditional now and off for now, so that it can be tested further;
can be turned on by adjusting ubc_direct variable to true

part of fix for PR kern/53124


To generate a diff of this commit:
cvs rdiff -u -r1.94 -r1.95 src/sys/uvm/uvm_bio.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.