On Wed, 15 May 2013 13:43:59 -0500 Cliff Wickman <[email protected]> wrote:
> From: Cliff Wickman <[email protected]> > > Because addresses of each successive page structure are often descending > it is much faster to use read()'s, so set off info->flag_usemmap > while doing exclude_free_page(). > > Signed-off-by: Cliff Wickman <[email protected]> Sounds good. BTW, do you have a speed measurement like your another patch ? > I find this to speed the scan of page structures for a 1TB system from > 60sec to 30sec. Thanks Atsushi Kumagai > --- > makedumpfile.c | 15 ++++++++++++++- > 1 file changed, 14 insertions(+), 1 deletion(-) > > Index: makedumpfile.mmap/makedumpfile.c > =================================================================== > --- makedumpfile.mmap.orig/makedumpfile.c > +++ makedumpfile.mmap/makedumpfile.c > @@ -3925,9 +3925,18 @@ _exclude_free_page(void) > return TRUE; > } > > +/* > + * Note that this is a very lengthy process, even using mmap(2). The > + * page structures in the free lists are read one-at-a-time, but using > + * readpage_elf(), which reads an entire page. And addresses of each > + * successive page structure are often descending, which means that each > + * read is another mmap(2) operation. > + * It is much faster to use read()'s, so set off info->flag_usemmap here. > + */ > int > exclude_free_page(void) > { > + int save = info->flag_usemmap; > /* > * Check having necessary information. > */ > @@ -3961,8 +3970,12 @@ exclude_free_page(void) > /* > * Detect free pages and update 2nd-bitmap. > */ > - if (!_exclude_free_page()) > + info->flag_usemmap = 0; > + if (!_exclude_free_page()) { > + info->flag_usemmap = save; > return FALSE; > + } > + info->flag_usemmap = save; > > return TRUE; > } _______________________________________________ kexec mailing list [email protected] http://lists.infradead.org/mailman/listinfo/kexec
