Currently, sending an interprocessor interrupt (IPI) requires building up
a message dynamically which means memory allocation. But often times, we
will want to send an IPI in low level contexts where allocation is not
possible which may lead to a panic(). So create a per-cpu static array
for the message queue and use that instead.
Further, while we have two supplemental interrupts, we are currently only
using one of them. So use the second one for the most common IPI message
of all -- smp_send_reschedule(). This avoids ugly contention for locks
which in turn would require an IPI message ...
In general, this improves SMP performance, and in some cases allows the
SMP port to work in places it wouldn't before. Such as the PREEMPT_RT
state where the slab is protected by a per-cpu spin lock. If the slab
kmalloc/kfree were to put the task to sleep, and that task was actually
the IPI handler, then the system falls down yet again.
After running some various stress tests on the system, the static limit
of 5 messages seems to work. On the off chance even this overflows, we
simply panic(), and we can review that scenario to see if the limit needs
to be increased a bit more.
Signed-off-by: Yi Li <yi.li@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
This function takes an irq_handler_t function, but the prototype in
the header doesn't match the function definition. This is due to the
smp headers needing to avoid circular dependencies. So change the
function to take a simple pointer.
Signed-off-by: Graf Yang <graf.yang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
SMP systems require per-cpu local clock event devices in order to enable
HRT support. One a BF561, we can use local core timer for this purpose.
Originally, there was one global core-timer clock event device set up for
core A.
To accomplish this feat, we need to split the gptimer0/core timer logic
so that each is a standalone clock event. There is no requirement that
we only have one clock event source anyways. Once we have this, we just
define per-cpu clock event devices for each local core timer.
Signed-off-by: Yi Li <yi.li@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Bill Gatliff & David Brownell pointed out we were missing some
copyrights, and licensing terms in some of the files in
./arch/blackfin, so this fixes things, and cleans them up.
It also removes:
- verbose GPL text(refer to the top level ./COPYING file)
- file names (you are looking at the file)
- bug url (it's in the ./MAINTAINERS file)
- "or later" on GPL-2, when we did not have that right
It also allows some Blackfin-specific assembly files to be under a BSD
like license (for people to use them outside of Linux).
Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Blackfin dual core BF561 processor can support SMP like features.
https://docs.blackfin.uclinux.org/doku.php?id=linux-kernel:smp-like
In this patch, we provide SMP extend to BF561 kernel code
Signed-off-by: Graf Yang <graf.yang@analog.com>
Signed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Yi Li