Great to see this hitting the tree Warner, I have a few questions inline
below.
On 14/04/2016 22:47, Warner Losh wrote:
Author: imp
Date: Thu Apr 14 21:47:58 2016
New Revision: 298002
URL: https://svnweb.freebsd.org/changeset/base/298002
Log:
New CAM I/O scheduler for FreeBSD. The default I/O scheduler is the same
as before. The common scheduling bits have moved from inline code in
each of the CAM periph drivers into a library that implements the
default scheduling.
In addition, a number of rate-limiting and I/O preference options can
be enabled by adding CAM_IOSCHED_NETFLIX to your config file. A number
of extra stats are also maintained. CAM_IOSCHED_NETFLIX isn't on by
default because it uses a separate BIO_READ and BIO_WRITE queue, so
doesn't honor BIO_ORDERED between these two types of operations. We
already didn't honor it for BIO_DELETE, and we don't depend on
BIO_ORDERED between reads and writes anywhere in the system (it is
currently used with BIO_FLUSH in ZFS to make sure some writes are
complete before others start and as a poor-man's soft dependency in
one place in UFS where we won't be issuing READs until after the
operation completes). However, out of an abundance of caution, it
isn't enabled by default.
Plus, this also brings in NCQ TRIM support for those SSDs that support
it. A black list is also provided for known rogues that use NCQ trim
as an excuse to corrupt the drive. It was difficult to separate out
into a separate commit.
This code has run in production at Netflix for over a year now.
Sponsored by: Netflix, Inc
Differential Revision: https://reviews.freebsd.org/D4609
snip...
@@ -844,7 +920,7 @@ adadump(void *arg, void *virtual, vm_off
0,
NULL,
0,
- ada_default_timeout*1000);
+ 5*1000);
Not a fan of random constants, is there a reason why this is now just 5
instead if ada_default_timeout, merge issue perhaps?
snip...
@@ -1898,6 +2154,31 @@ out:
static int
adaerror(union ccb *ccb, u_int32_t cam_flags, u_int32_t sense_flags)
{
+ struct ada_softc *softc;
+ struct cam_periph *periph;
+
+ periph = xpt_path_periph(ccb->ccb_h.path);
+ softc = (struct ada_softc *)periph->softc;
+
+ switch (ccb->ccb_h.status & CAM_STATUS_MASK) {
+ case CAM_CMD_TIMEOUT:
+#ifdef CAM_IO_STATS
+ softc->timeouts++;
+#endif
+ break;
+ case CAM_REQ_ABORTED:
+ case CAM_REQ_CMP_ERR:
+ case CAM_REQ_TERMIO:
+ case CAM_UNREC_HBA_ERROR:
+ case CAM_DATA_RUN_ERR:
+ case CAM_ATA_STATUS_ERROR:
+#ifdef CAM_IO_STATS
+ softc->errors++;
+#endif
+ break;
+ default:
+ break;
+ }
Am I missing something or does this entire switch do nothing unless
CAM_IO_STATS is set and hence could all be under the #ifdef?
Regards
Steve
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