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.
The defined now safety requirements are:
- caller should not hold any locks and should be reenterable;
- callee should not depend on GEOM dual-threaded concurency semantics;
- on the way down, if request is unmapped while callee doesn't support it,
the context should be sleepable;
- kernel thread stack usage should be below 50%.
To keep compatibility with GEOM classes not meeting above requirements
new provider and consumer flags added:
- G_CF_DIRECT_SEND -- consumer code meets caller requirements (request);
- G_CF_DIRECT_RECEIVE -- consumer code meets callee requirements (done);
- G_PF_DIRECT_SEND -- provider code meets caller requirements (done);
- G_PF_DIRECT_RECEIVE -- provider code meets callee requirements (request).
Capable GEOM class can set them, allowing direct dispatch in cases where
it is safe. If any of requirements are not met, request is queued to
g_up or g_down thread same as before.
Such GEOM classes were reviewed and updated to support direct dispatch:
CONCAT, DEV, DISK, GATE, MD, MIRROR, MULTIPATH, NOP, PART, RAID, STRIPE,
VFS, ZERO, ZFS::VDEV, ZFS::ZVOL, all classes based on g_slice KPI (LABEL,
MAP, FLASHMAP, etc).
To declare direct completion capability disk(9) KPI got new flag equivalent
to G_PF_DIRECT_SEND -- DISKFLAG_DIRECT_COMPLETION. da(4) and ada(4) disk
drivers got it set now thanks to earlier CAM locking work.
This change more then twice increases peak block storage performance on
systems with manu CPUs, together with earlier CAM locking changes reaching
more then 1 million IOPS (512 byte raw reads from 16 SATA SSDs on 4 HBAs to
256 user-level threads).
Sponsored by: iXsystems, Inc.
MFC after: 2 months
would resize a partition, but label providers - e.g. /dev/gptid/XXX - would
stay the same size.
Reviewed by: mav
MFC after: 1 month
Sponsored by: FreeBSD Foundation
It includes three parts:
1) Modifications to CAM to detect media media changes and report them to
disk(9) layer. For modern SATA (and potentially UAS) devices it utilizes
Asynchronous Notification mechanism to receive events from hardware.
Active polling with TEST UNIT READY commands with 3 seconds period is used
for incapable hardware. After that both CD and DA drivers work the same way,
detecting two conditions: "NOT READY: Medium not present" after medium was
detected previously, and "UNIT ATTENTION: Not ready to ready change, medium
may have changed". First one reported to disk(9) as media removal, second
as media insert/change. To reliably receive second event new
AC_UNIT_ATTENTION async added to make UAs broadcasted to all periphs by
generic error handling code in cam_periph_error().
2) Modifications to GEOM core to handle media remove and change events.
Media removal handled by spoiling all consumers attached to the provider.
Media change event also schedules provider retaste after spoiling to probe
new media. New flag G_CF_ORPHAN was added to consumers to reflect that
consumer is in process of destruction. It allows retaste to create new
geom instance of the same class, while previous one is still dying.
3) Modifications to some GEOM classes: DEV -- to report media change
events to devd; VFS -- to handle spoiling same as orphan to prevent
accessing replaced media. PART class already handles spoiling alike to
orphan.
Reviewed by: silence on geom@ and scsi@
Tested by: avg
Sponsored by: iXsystems, Inc. / PC-BSD
MFC after: 2 months
is an error set on the provider. With GEOM resizing, class can become
orphaned when it doesn't implement resize() method and the provider size
decreases.
Reviewed by: mav
Sponsored by: FreeBSD Foundation
zero stripeoffset in such case (as if device has no stripes), report offset
from the beginning of the media (as if device has single infinite stripe).
This gives partitioning tools information, required to guess better
partition alignment, in case if hardware doesn't report it's stripe size.
For example, it should give disklabel info about odd offset made by fdisk.
particular provider. Use this function where g_orphan_provider()
is being called so that the flags are updated correctly and
g_orphan_provider() is called only when allowed.
it is destroyed in GEOM, in addition to being removed from /dev.
Before this patch, if you applied a new MBR which deleted a slice,
the deleted slice would not be in /dev, but it would still appear
in kern.geom.conftxt and kern.geom.confxml, which would confused
the diskPartitionEditor in sysinstall.
Submitted by: pjd
Tested by: pjd, rodrigc
MFC after: 1 week
shown that it is not useful.
Rename the relative count g_access_rel() function to g_access(), only
the name has changed.
Change all g_access_rel() calls in our CVS tree to call g_access() instead.
Add an #ifndef BURN_BRIDGES #define of g_access_rel() for source
code compatibility.
test is built to test GEOM as running in the kernel.
This commit is basically "unifdef -D_KERNEL" to remove the mainly #include
related code to support the userland-harness.
and d_stripesisze;
Introduce si_stripesize and si_stripeoffset in struct cdev so we
can make the visible to clustering code.
Add stripesize and stripeoffset to providers.
DTRT with stripesize and stripeoffset in various places in GEOM.
WARNING: This is not a published interface, it is a stopgap measure for
WARNING: libdisk so we can get 5.0-R out of the door.
Sponsored by: DARPA & NAI Labs
This is not quite the set of information I would want, but the tree where
I have the "correct" version is messed up with conflicts.
Sponsored by: DARPA & NAI Labs.
don't take the detour over the I/O path to discover them using getattr(),
we can just pick them out directly.
Do note though, that for now they are only valid after the first open
of the underlying disk device due compatibility with the old disk_create()
API. This will change in the future so they will always be valid.
Sponsored by: DARPA & NAI Labs.
