CVSROOT: /cvs Module name: src Changes by: s...@cvs.openbsd.org 2017/05/29 07:48:12
Modified files: sys/msdosfs : denode.h msdosfs_vnops.c Log message: Implement VFS read clustering for MSDOSFS This is the reverted commit by mpi@ from msdosfs_vnops.c 1.105 plus some additional tweaks to fix some cluster/block number confusion that lead to regressions when seeking past the end of a file. The original commit message was: The logic used in msdosfs_bmap() to loop calling pcbmap() comes from FreeBSD and is not really efficient but it is good enough since it is only called when generating I/O. With this diff I get a 100% improvement when reading big files from a crappy USB stick. With this and bread_cluster(9) modified to not re-fetch B_CACHED buffers, reading large contiguous files with chunk sizes of MAXPHYS is almost as fast as physio(9) on the same device. For a 'real world' example, when copying music files from a USB stick I see a speed jump from 15MB/s on -current to 24Mb/s with this diff. While here rename some 'lbn' variables into 'cn' to better reflect what we're dealing with. Tested by Mathieu, with support from deraadt@ ok mpi@