On 03/09/2013 12:31 PM, HATAYAMA Daisuke wrote: > From: Jingbai Ma<jingbai.ma at hp.com> > Subject: Re: [RFC PATCH 0/5] crash dump bitmap: scan memory pages in kernel to speedup kernel dump process > Date: Fri, 8 Mar 2013 18:06:31 +0800 > >> On 03/07/2013 11:21 PM, Vivek Goyal wrote: >>> On Thu, Mar 07, 2013 at 10:58:18PM +0800, Jingbai Ma wrote: > ... >>> First of all 64MB per TB should not be a huge deal. And makedumpfile >>> also has this cyclic mode where you process a map, discard it and then >>> move on to next section. So memory usage remains constant at the >>> expense >>> of processing time. >> >> Yes, that's true. But in cyclic mode, makedumpfile will have to >> write/read bitmap from storage, it will also impact the performance. >> I have measured the penalty for cyclic mode is about 70% >> slowdown. Maybe could be faster after mmap implemented. > > I guess the slowdown came from the issue that enough VMCOREINFO was > not provided from the kernel, and unnecessary filtering processing for > free pages is done multiple times. Thanks for your comments! It would be very helpful. I will test it on the machine again. -- Jingbai Ma (jingbai.ma at hp.com)
