| Message ID | 20170316085545.EEE4A68481@localhost.localdomain (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 45cb08f4791ce6a15c54598b4cb73db4b4b8294f |
| Headers | show |
On Thu, 2017-03-16 at 08:55:45 UTC, Christophe Leroy wrote: > It often happens to have simultaneous interrupts, for instance > when having double Ethernet attachment. With the current > implementation, we suffer the cost of kernel entry/exit for each > interrupt. > > This patch introduces a loop in __do_irq() to handle all interrupts > at once before returning. > > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/45cb08f4791ce6a15c54598b4cb73d cheers
On Mon, 2017-06-05 at 20:21 +1000, Michael Ellerman wrote: > On Thu, 2017-03-16 at 08:55:45 UTC, Christophe Leroy wrote: > > It often happens to have simultaneous interrupts, for instance > > when having double Ethernet attachment. With the current > > implementation, we suffer the cost of kernel entry/exit for each > > interrupt. > > > > This patch introduces a loop in __do_irq() to handle all interrupts > > at once before returning. > > > > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> > > Applied to powerpc next, thanks. > > https://git.kernel.org/powerpc/c/45cb08f4791ce6a15c54598b4cb73d Hrm, I hadn't noticed that patch... We used to do that and then removed the code for it. There's a cost, sometimes noticeable, to an extra call to ppc_md.get_irq. Why not have your get_irq (or eoi) implementation set a per-cpu requesting a new spin of the loop ? We could move the xive force replay stuff to use the same thing. Ben.
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c index a018f5cae899..ba0cb6c2ee7d 100644 --- a/arch/powerpc/kernel/irq.c +++ b/arch/powerpc/kernel/irq.c @@ -522,7 +522,11 @@ void __do_irq(struct pt_regs *regs) if (unlikely(!irq)) __this_cpu_inc(irq_stat.spurious_irqs); else - generic_handle_irq(irq); + do { + generic_handle_irq(irq); + + irq = ppc_md.get_irq(); + } while (irq); trace_irq_exit(regs);
It often happens to have simultaneous interrupts, for instance when having double Ethernet attachment. With the current implementation, we suffer the cost of kernel entry/exit for each interrupt. This patch introduces a loop in __do_irq() to handle all interrupts at once before returning. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> --- Changed from v1(RFC): simplified following remark from benh arch/powerpc/kernel/irq.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)