Messages in this thread | | | From | Marc Zyngier <> | Subject | [PATCH v4 0/2] irqchip/gic-v3-its: Balance LPI affinity across CPUs | Date | Fri, 15 May 2020 17:57:50 +0100 |
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When mapping a LPI, the ITS driver picks the first possible affinity, which is in most cases CPU0, assuming that if that's not suitable, someone will come and set the affinity to something more interesting.
It apparently isn't the case, and people complain of poor performance when many interrupts are glued to the same CPU. So let's place the interrupts by finding the "least loaded" CPU (that is, the one that has the fewer LPIs mapped to it). So called 'managed' interrupts are an interesting case where the affinity is actually dictated by the kernel itself, and we should honor this.
* From v3: - Always pre-decrement/post-increment affinity to avoid useless changes of affinity (John) - Don't use the node mask as a superset of the proposed affinity as the ACPI tables can't really describe this (John) - Rebased on v5.7-rc5
* From v2: - Split accounting from CPU selection - Track managed and unmanaged interrupts separately
Marc Zyngier (2): irqchip/gic-v3-its: Track LPI distribution on a per CPU basis irqchip/gic-v3-its: Balance initial LPI affinity across CPUs
drivers/irqchip/irq-gic-v3-its.c | 170 ++++++++++++++++++++++++++----- 1 file changed, 143 insertions(+), 27 deletions(-)
-- 2.26.2
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