From fda9d86100e0b412d0c8a16abe0651c8c8e39e81 Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Sun, 31 Jan 2010 20:32:51 +0000 Subject: powerpc: Reduce footprint of xics_ipi_struct Right now we allocate a cacheline sized NR_CPUS array for xics IPI communication. Use DECLARE_PER_CPU_SHARED_ALIGNED to put it in percpu data in its own cacheline since it is written to by other cpus. On a kernel with NR_CPUS=1024, this saves quite a lot of memory: text data bss dec hex filename 8767779 2944260 1505724 13217763 c9afe3 vmlinux.irq_cpustat 8767555 2813444 1505724 13086723 c7b003 vmlinux.xics A saving of around 128kB. Signed-off-by: Anton Blanchard Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/platforms/pseries/xics.c | 26 +++++++++++--------------- 1 file changed, 11 insertions(+), 15 deletions(-) (limited to 'arch/powerpc/platforms') diff --git a/arch/powerpc/platforms/pseries/xics.c b/arch/powerpc/platforms/pseries/xics.c index 63eaa8a220c..41374e830eb 100644 --- a/arch/powerpc/platforms/pseries/xics.c +++ b/arch/powerpc/platforms/pseries/xics.c @@ -510,15 +510,13 @@ static void __init xics_init_host(void) /* * XICS only has a single IPI, so encode the messages per CPU */ -struct xics_ipi_struct { - unsigned long value; - } ____cacheline_aligned; - -static struct xics_ipi_struct xics_ipi_message[NR_CPUS] __cacheline_aligned; +static DEFINE_PER_CPU_SHARED_ALIGNED(unsigned long, xics_ipi_message); static inline void smp_xics_do_message(int cpu, int msg) { - set_bit(msg, &xics_ipi_message[cpu].value); + unsigned long *tgt = &per_cpu(xics_ipi_message, cpu); + + set_bit(msg, tgt); mb(); if (firmware_has_feature(FW_FEATURE_LPAR)) lpar_qirr_info(cpu, IPI_PRIORITY); @@ -544,25 +542,23 @@ void smp_xics_message_pass(int target, int msg) static irqreturn_t xics_ipi_dispatch(int cpu) { + unsigned long *tgt = &per_cpu(xics_ipi_message, cpu); + WARN_ON(cpu_is_offline(cpu)); mb(); /* order mmio clearing qirr */ - while (xics_ipi_message[cpu].value) { - if (test_and_clear_bit(PPC_MSG_CALL_FUNCTION, - &xics_ipi_message[cpu].value)) { + while (*tgt) { + if (test_and_clear_bit(PPC_MSG_CALL_FUNCTION, tgt)) { smp_message_recv(PPC_MSG_CALL_FUNCTION); } - if (test_and_clear_bit(PPC_MSG_RESCHEDULE, - &xics_ipi_message[cpu].value)) { + if (test_and_clear_bit(PPC_MSG_RESCHEDULE, tgt)) { smp_message_recv(PPC_MSG_RESCHEDULE); } - if (test_and_clear_bit(PPC_MSG_CALL_FUNC_SINGLE, - &xics_ipi_message[cpu].value)) { + if (test_and_clear_bit(PPC_MSG_CALL_FUNC_SINGLE, tgt)) { smp_message_recv(PPC_MSG_CALL_FUNC_SINGLE); } #if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC) - if (test_and_clear_bit(PPC_MSG_DEBUGGER_BREAK, - &xics_ipi_message[cpu].value)) { + if (test_and_clear_bit(PPC_MSG_DEBUGGER_BREAK, tgt)) { smp_message_recv(PPC_MSG_DEBUGGER_BREAK); } #endif -- cgit v1.2.3