For channel0, it will never be processed on event handling path,
so there is no need to install it. After skipping in the channel0
installation, we could discard the channel0 check on event
handling hot code path.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6333
Currently, Application Processors (non-boot CPUs) are started by
MD code at SI_SUB_CPU, but they are kept waiting in a "pen" until
SI_SUB_SMP at which point they are released to run kernel threads.
SI_SUB_SMP is one of the last SYSINIT levels, so APs don't enter
the scheduler and start running threads until fairly late in the
boot.
This change moves SI_SUB_SMP up to just before software interrupt
threads are created allowing the APs to start executing kernel
threads much sooner (before any devices are probed). This allows
several initialization routines that need to perform initialization
on all CPUs to now perform that initialization in one step rather
than having to defer the AP initialization to a second SYSINIT run
at SI_SUB_SMP. It also permits all CPUs to be available for
handling interrupts before any devices are probed.
This last feature fixes a problem on with interrupt vector exhaustion.
Specifically, in the old model all device interrupts were routed
onto the boot CPU during boot. Later after the APs were released at
SI_SUB_SMP, interrupts were redistributed across all CPUs.
However, several drivers for multiqueue hardware allocate N interrupts
per CPU in the system. In a system with many CPUs, just a few drivers
doing this could exhaust the available pool of interrupt vectors on
the boot CPU as each driver was allocating N * mp_ncpu vectors on the
boot CPU. Now, drivers will allocate interrupts on their desired CPUs
during boot meaning that only N interrupts are allocated from the boot
CPU instead of N * mp_ncpu.
Some other bits of code can also be simplified as smp_started is
now true much earlier and will now always be true for these bits of
code. This removes the need to treat the single-CPU boot environment
as a special case.
As a transition aid, the new behavior is available under a new kernel
option (EARLY_AP_STARTUP). This will allow the option to be turned off
if need be during initial testing. I plan to enable this on x86 by
default in a followup commit in the next few days and to have all
platforms moved over before 11.0. Once the transition is complete,
the option will be removed along with the !EARLY_AP_STARTUP code.
These changes have only been tested on x86. Other platform maintainers
are encouraged to port their architectures over as well. The main
things to check for are any uses of smp_started in MD code that can be
simplified and SI_SUB_SMP SYSINITs in MD code that can be removed in
the EARLY_AP_STARTUP case (e.g. the interrupt shuffling).
PR: kern/199321
Reviewed by: markj, gnn, kib
Sponsored by: Netflix
On WIN8 like host systems, when rescan happens, the already installed
disks seem to return random invalid results for INQUIRY.
More investigation is under way to figure out why random invalid INQUIRY
results are delivered to VM on WIN8 like host systems.
Submitted by: Hongjiang Zhang <honzhan microsoft com>
Reviewed by: sephe
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6316
This greatly reduces the oqdrops under heavy workload.
For TCP send/recv test (10K concurrent connections):
oqdrops is reduced by 17% on sending side, and 57% on receiving side.
For nginx-1.8/wrk-4 1KB object test (10K concurrent connections,
4 requests/connection):
oqdrops is reduced by 44% on nginx side, and 10% on wrk side.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Since the sub-channel offers are synchronized, we can do our own
channel setup without using the sub-channel creation callback.
This paves the way to whack the sub-channel creation callback.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Since the sub-channel offers are synchronized, we can do our own
channel setup without using the sub-channel creation callback.
This paves the way to whack the sub-channel creation callback.
MFC after: 1 week
Sponsored by: Microsoft OSTC
This fixes the sub-channel offer race after Hyper-V device probe/attach
is moved to vmbus SYSINIT/attach.
MFC after: 1 week
Sponsored by: Microsoft OSTC
Submitted by: Jun Su <junsu microsoft com>
Reviewed by: sephe, Dexuan Cui <decui microsoft com>
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D5957
Submitted by: Jun Su <junsu microsoft com>
Reviewed by: jhb, kib, sephe
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D5910
8 gives the best performance in both Azure and local Hyper-V on both
10Ge and 40Ge. More rings are still allowed by manual configuration.
Reviewed by: Dexuan Cui <decui microsoft com>
MFC after: 1 week
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D5879
