MFC Alexander Motin's GEOM direct dispatch work:

r256603:
Introduce new function devstat_end_transaction_bio_bt(), adding new argument
to specify present time.  Use this function to move binuptime() out of lock,
substantially reducing lock congestion when slow timecounter is used.

r256606:
Move g_io_deliver() out of the lock, as required for direct dispatch.
Move g_destroy_bio() out too to reduce lock scope even more.

r256607:
Fix passing uninitialized bio_resid argument to g_trace().

r256610:
Add unmapped I/O support to GEOM RAID.

r256830:
Restore BIO_UNMAPPED and BIO_TRANSIENT_MAPPING in biodonne() when unmapping
temporary mapped buffer.  That fixes double unmap if biodone() called twice
for the same BIO (but with different done methods).

r256880:
Merge GEOM direct dispatch changes from the projects/camlock branch.

When safety requirements are met, it allows to avoid passing I/O requests
to GEOM g_up/g_down thread, executing them directly in the caller context.
That allows to avoid CPU bottlenecks in g_up/g_down threads, plus avoid
several context switches per I/O.

r259247:
Fix bug introduced at r256607.  We have to recalculate bp_resid here since
sizes of original and completed requests may differ due to end of media.

Testing of the stable/10 merge was done by Netflix, but all of the credit
goes to Alexander and iX Systems.

Submitted by:   mav
Sponsored by:   iX Systems

1 files changed, 7 insertions, 0 deletions

diff --git a/sys/geom/geom_kern.c b/sys/geom/geom_kern.c
index 2e65bfb..79afb14 100644
--- a/sys/geom/geom_kern.c
+++ b/sys/geom/geom_kern.c
@@ -124,6 +124,13 @@ g_event_procbody(void *arg)
 	/* NOTREACHED */
 }
 
+int
+g_is_geom_thread(struct thread *td)
+{
+
+	return (td == g_up_td || td == g_down_td || td == g_event_td);
+}
+
 static void
 geom_shutdown(void *foo __unused)
 {