Poul-Henning Kamp 56dd3a6182 Add optional device vnode bypass to DEVFS. ... The tunable vfs.devfs.fops controls this feature and defaults to off. When enabled (vfs.devfs.fops=1 in loader), device vnodes opened through a filedescriptor gets a special fops vector which instead of the detour through the vnode layer goes directly to DEVFS. Amongst other things this allows us to run Giant free read/write to device drivers which have been weaned off D_NEEDGIANT. Currently this means /dev/null, /dev/zero, disks, (and maybe the random stuff ?) On a 700MHz K7 machine this doubles the speed of dd if=/dev/zero of=/dev/null bs=1 count=1000000 This roughly translates to shaving 2usec of each read/write syscall. The poll/kqfilter paths need more work before they are giant free, this work is ongoing in p4::phk_bufwork Please test this and report any problems, LORs etc.		2004-11-08 10:46:47 +00:00
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devfs.h	Do the dreaded s/dev_t/struct cdev */	2004-06-16 09:47:26 +00:00
devfs_devs.c	Reduce a fair bit of the atomics because we are now called with a	2004-06-18 08:08:47 +00:00
devfs_rule.c	XXX mark two places where we do not hold a threadcount on the dev when	2004-09-24 08:32:36 +00:00
devfs_vfsops.c	What can I say: don't allow people to mount DEVFS with option "nodev".	2004-10-28 06:03:25 +00:00
devfs_vnops.c	Add optional device vnode bypass to DEVFS.	2004-11-08 10:46:47 +00:00