Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758465Ab0KSWR0 (ORCPT ); Fri, 19 Nov 2010 17:17:26 -0500 Received: from kroah.org ([198.145.64.141]:52878 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758007Ab0KSWEK (ORCPT ); Fri, 19 Nov 2010 17:04:10 -0500 X-Mailbox-Line: From gregkh@clark.site Fri Nov 19 14:01:23 2010 Message-Id: <20101119220123.488019055@clark.site> User-Agent: quilt/0.48-11.2 Date: Fri, 19 Nov 2010 14:00:47 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Cliff Wickman , kexec@lists.infradead.org, Ingo Molnar Subject: [16/66] mm, x86: Saving vmcore with non-lazy freeing of vmas In-Reply-To: <20101119220309.GA15562@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2350 Lines: 78 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. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/