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  1. 16 Jul, 2018 3 commits
    • Marc Zyngier's avatar
      irqchip/gic-v3-its: Move minimum LPI requirements to individual busses · 147c8f37
      Marc Zyngier authored 
      At the moment, the core ITS driver imposes the allocation to be
in chunks of 32. As we want to relax this on a per bus basis, let's
move the the the allocation constraints to each bus.

No functionnal change.
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
      147c8f37
    • Marc Zyngier's avatar
      irqchip/gic-v3-its: Use full range of LPIs · fe8e9350
      Marc Zyngier authored 
      As we used to represent the LPI range using a bitmap, we were reducing
the number of LPIs to at most 64k in order to preserve memory.

With our new allocator, there is no such need, as dealing with 2^16
or 2^32 LPIs takes the same amount of memory.

So let's use the number of IntID bits reported by the GIC instead of
an arbitrary limit.
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
      fe8e9350
    • Marc Zyngier's avatar
      irqchip/gic-v3-its: Refactor LPI allocator · 880cb3cd
      Marc Zyngier authored 
      Our current LPI allocator relies on a bitmap, each bit representing
a chunk of 32 LPIs, meaning that each device gets allocated LPIs
in multiple of 32. It served us well so far, but new use cases now
require much more finer grain allocations, down the the individual
LPI.

Given the size of the IntID space (up to 32bit), it isn't practical
to continue using a bitmap, so let's use a different data structure
altogether.

We switch to a list, where each element represent a contiguous range
of LPIs. On allocation, we simply grab the first group big enough to
satisfy the allocation, and substract what we need from it. If the
group becomes empty, we just remove it. On freeing interrupts, we
insert a new group of interrupt in the list, sort it and fuse the
adjacent groups.

This makes freeing interrupt much more expensive than allocating
them (an unusual behaviour), but that's fine as long as we consider
that freeing interrupts is an extremely rare event.

We still allocate interrupts in blocks of 32 for the time being,
but subsequent patches will relax this.
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
      880cb3cd
  3. 15 Jul, 2018 2 commits
  5. 14 Jul, 2018 19 commits
  7. 13 Jul, 2018 15 commits
  9. 12 Jul, 2018 1 commit
    • Joel Fernandes (Google)'s avatar
      tracing: Reorder display of TGID to be after PID · f8494fa3
      Joel Fernandes (Google) authored 
      Currently ftrace displays data in trace output like so:

                                       _-----=> irqs-off
                                      / _----=> need-resched
                                     | / _---=> hardirq/softirq
                                     || / _--=> preempt-depth
                                     ||| /     delay
            TASK-PID   CPU    TGID   ||||    TIMESTAMP  FUNCTION
               | |       |      |    ||||       |         |
            bash-1091  [000] ( 1091) d..2    28.313544: sched_switch:

However Android's trace visualization tools expect a slightly different
format due to an out-of-tree patch patch that was been carried for a
decade, notice that the TGID and CPU fields are reversed:

                                       _-----=> irqs-off
                                      / _----=> need-resched
                                     | / _---=> hardirq/softirq
                                     || / _--=> preempt-depth
                                     ||| /     delay
            TASK-PID    TGID   CPU   ||||    TIMESTAMP  FUNCTION
               | |        |      |   ||||       |         |
            bash-1091  ( 1091) [002] d..2    64.965177: sched_switch:

From kernel v4.13 onwards, during which TGID was introduced, tracing
with systrace on all Android kernels will break (most Android kernels
have been on 4.9 with Android patches, so this issues hasn't been seen
yet). From v4.13 onwards things will break.

The chrome browser's tracing tools also embed the systrace viewer which
uses the legacy TGID format and updates to that are known to be
difficult to make.

Considering this, I suggest we make this change to the upstream kernel
and backport it to all Android kernels. I believe this feature is merged
recently enough into the upstream kernel that it shouldn't be a problem.
Also logically, IMO it makes more sense to group the TGID with the
TASK-PID and the CPU after these.

Link: http://lkml.kernel.org/r/20180626000822.113931-1-joel@joelfernandes.org

Cc: jreck@google.com
Cc: tkjos@google.com
Cc: stable@vger.kernel.org
Fixes: 441dae8f ("tracing: Add support for display of tgid in trace output")
Signed-off-by: default avatarJoel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
      f8494fa3
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