From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from kroah.org ([198.145.64.141] helo=coco.kroah.org) by canuck.infradead.org with esmtps (Exim 4.72 #1 (Red Hat Linux)) id 1PJZ3y-0002D8-QK for kexec@lists.infradead.org; Fri, 19 Nov 2010 22:04:11 +0000 Message-Id: <20101119220123.488019055@clark.site> Date: Fri, 19 Nov 2010 14:00:47 -0800 From: Greg KH Subject: [16/66] mm, x86: Saving vmcore with non-lazy freeing of vmas In-Reply-To: <20101119220309.GA15562@kroah.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: Ingo Molnar , kexec@lists.infradead.org, Cliff Wickman , akpm@linux-foundation.org, torvalds@linux-foundation.org, stable-review@kernel.org, alan@lxorguk.ukuu.org.uk 2.6.36-stable review patch. If anyone has any objections, please let us know. ------------------ From: Cliff Wickman commit 3ee48b6af49cf534ca2f481ecc484b156a41451d upstream. During the reading of /proc/vmcore the kernel is doing ioremap()/iounmap() repeatedly. And the buildup of un-flushed vm_area_struct's is causing a great deal of overhead. (rb_next() is chewing up most of that time). This solution is to provide function set_iounmap_nonlazy(). It causes a subsequent call to iounmap() to immediately purge the vma area (with try_purge_vmap_area_lazy()). With this patch we have seen the time for writing a 250MB compressed dump drop from 71 seconds to 44 seconds. Signed-off-by: Cliff Wickman Cc: Andrew Morton Cc: kexec@lists.infradead.org LKML-Reference: Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/io.h | 1 + arch/x86/kernel/crash_dump_64.c | 1 + mm/vmalloc.c | 9 +++++++++ 3 files changed, 11 insertions(+) --- a/arch/x86/include/asm/io.h +++ b/arch/x86/include/asm/io.h @@ -206,6 +206,7 @@ static inline void __iomem *ioremap(reso extern void iounmap(volatile void __iomem *addr); +extern void set_iounmap_nonlazy(void); #ifdef __KERNEL__ --- a/arch/x86/kernel/crash_dump_64.c +++ b/arch/x86/kernel/crash_dump_64.c @@ -46,6 +46,7 @@ ssize_t copy_oldmem_page(unsigned long p } else memcpy(buf, vaddr + offset, csize); + set_iounmap_nonlazy(); iounmap(vaddr); return csize; } --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -517,6 +517,15 @@ static atomic_t vmap_lazy_nr = ATOMIC_IN static void purge_fragmented_blocks_allcpus(void); /* + * called before a call to iounmap() if the caller wants vm_area_struct's + * immediately freed. + */ +void set_iounmap_nonlazy(void) +{ + atomic_set(&vmap_lazy_nr, lazy_max_pages()+1); +} + +/* * Purges all lazily-freed vmap areas. * * If sync is 0 then don't purge if there is already a purge in progress. _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec