CVS commit: [jdolecek-ncq] src/sys/dev/ata

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

Module Name:    src
Committed By:   jdolecek
Date:           Fri Jun 23 20:40:51 UTC 2017

Modified Files:
        src/sys/dev/ata [jdolecek-ncq]: TODO.ncq ata.c atavar.h wd.c wdvar.h

Log Message:
restart I/O processing after freeing xfer, i.e. now even after commands
like cache flush or standby; the command handling no longer use on-stack xfer,
hence use queue slot and compete with normal I/O for the xfers

the restart give change to all drives attached to the same channel
in round-robin fashion, for fair usage and to recover from situation
when disk is idle due to all xfers being consumed by other drives

make special concession for flush cache - ignore any new I/O requests
on the particular disk while the flush cache is waiting for xfer,
so that I/O queue won't starve the flush cache and the flush cache would
be done ASAP

tested on piixide(4), ahci(4), siisata(4)


To generate a diff of this commit:
cvs rdiff -u -r1.1.2.21 -r1.1.2.22 src/sys/dev/ata/TODO.ncq
cvs rdiff -u -r1.132.8.15 -r1.132.8.16 src/sys/dev/ata/ata.c
cvs rdiff -u -r1.92.8.14 -r1.92.8.15 src/sys/dev/ata/atavar.h
cvs rdiff -u -r1.428.2.19 -r1.428.2.20 src/sys/dev/ata/wd.c
cvs rdiff -u -r1.43.4.5 -r1.43.4.6 src/sys/dev/ata/wdvar.h

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