From 19df0c2fef010e94e90df514aaf4e73f6b80145c Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 25 Jan 2011 14:26:50 +0100 Subject: percpu: align percpu readmostly subsection to cacheline Currently percpu readmostly subsection may share cachelines with other percpu subsections which may result in unnecessary cacheline bounce and performance degradation. This patch adds @cacheline parameter to PERCPU() and PERCPU_VADDR() linker macros, makes each arch linker scripts specify its cacheline size and use it to align percpu subsections. This is based on Shaohua's x86 only patch. Signed-off-by: Tejun Heo Cc: Shaohua Li --- arch/s390/kernel/vmlinux.lds.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/s390/kernel/vmlinux.lds.S') diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S index a68ac10213b2..1bc18cdb525b 100644 --- a/arch/s390/kernel/vmlinux.lds.S +++ b/arch/s390/kernel/vmlinux.lds.S @@ -77,7 +77,7 @@ SECTIONS . = ALIGN(PAGE_SIZE); INIT_DATA_SECTION(0x100) - PERCPU(PAGE_SIZE) + PERCPU(0x100, PAGE_SIZE) . = ALIGN(PAGE_SIZE); __init_end = .; /* freed after init ends here */ -- cgit v1.2.2 From 0415b00d175e0d8945e6785aad21b5f157976ce0 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 24 Mar 2011 18:50:09 +0100 Subject: percpu: Always align percpu output section to PAGE_SIZE Percpu allocator honors alignment request upto PAGE_SIZE and both the percpu addresses in the percpu address space and the translated kernel addresses should be aligned accordingly. The calculation of the former depends on the alignment of percpu output section in the kernel image. The linker script macros PERCPU_VADDR() and PERCPU() are used to define this output section and the latter takes @align parameter. Several architectures are using @align smaller than PAGE_SIZE breaking percpu memory alignment. This patch removes @align parameter from PERCPU(), renames it to PERCPU_SECTION() and makes it always align to PAGE_SIZE. While at it, add PCPU_SETUP_BUG_ON() checks such that alignment problems are reliably detected and remove percpu alignment comment recently added in workqueue.c as the condition would trigger BUG way before reaching there. For um, this patch raises the alignment of percpu area. As the area is in .init, there shouldn't be any noticeable difference. This problem was discovered by David Howells while debugging boot failure on mn10300. Signed-off-by: Tejun Heo Acked-by: Mike Frysinger Cc: uclinux-dist-devel@blackfin.uclinux.org Cc: David Howells Cc: Jeff Dike Cc: user-mode-linux-devel@lists.sourceforge.net --- arch/s390/kernel/vmlinux.lds.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/s390/kernel/vmlinux.lds.S') diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S index 1bc18cdb525b..56fe6bc81fee 100644 --- a/arch/s390/kernel/vmlinux.lds.S +++ b/arch/s390/kernel/vmlinux.lds.S @@ -77,7 +77,7 @@ SECTIONS . = ALIGN(PAGE_SIZE); INIT_DATA_SECTION(0x100) - PERCPU(0x100, PAGE_SIZE) + PERCPU_SECTION(0x100) . = ALIGN(PAGE_SIZE); __init_end = .; /* freed after init ends here */ -- cgit v1.2.2