[Xen-devel] [PATCH v4] Fix interrupt latency of HVM PCI passthrough devices.

[konrad@xxxxxxxxxx]

Please see this patch which I hope meets your standards.

There are two pieces of code that might be a bit odd:

 1). The usage of 'int cpu = smp_processor_id()' and then using
     it just once, instead of using '*this_cpu' in schedule_dpci_for.
     The reason is that Andrew pointed out to me (in the tasklet review)
     that we want to spend as little time as possible in the critical code
     and hence moving the 'cpu = smp_processor_id()' out would
     do that.

 2). The assert:

        ASSERT(list_empty(&per_cpu(dpci_list, cpu)));

     Other code in the hypervisor has 'ASSERT( list_empty..') but the
     syntax in the io.c file is to have no spaces in the ASSERT.
     If you would like it to be the same - ASSERT( x ), I can prepare
     a cleanup patch to fix that.

Otherwise it should be all good.

 xen/arch/x86/domain.c         |    4 +-
 xen/drivers/passthrough/io.c  |  168 ++++++++++++++++++++++++++++++++++++++--
 xen/drivers/passthrough/pci.c |   24 +++++--
 xen/include/xen/hvm/irq.h     |    2 +-
 xen/include/xen/pci.h         |    2 +-
 xen/include/xen/sched.h       |    6 ++
 xen/include/xen/softirq.h     |    3 +
 7 files changed, 191 insertions(+), 18 deletions(-)

Konrad Rzeszutek Wilk (1):
      dpci: Replace tasklet with an softirq (v4)


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