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Date: Thu, 17 Aug 2017 13:28:06 +0200 From: Michal Hocko <mhocko@...nel.org> To: Chen Yu <yu.c.chen@...el.com> Cc: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>, Mel Gorman <mgorman@...hsingularity.net>, Vlastimil Babka <vbabka@...e.cz>, "Rafael J. Wysocki" <rjw@...ysocki.net>, Len Brown <lenb@...nel.org>, Dan Williams <dan.j.williams@...el.com>, linux-kernel@...r.kernel.org Subject: Re: [PATCH][RFC v3] PM / Hibernate: Feed the wathdog when creating snapshot On Thu 17-08-17 12:04:34, Chen Yu wrote: [...] > #ifdef CONFIG_HIBERNATION > > +/* Touch watchdog for every WD_INTERVAL_PAGE pages. */ > +#define WD_INTERVAL_PAGE 1000 traversing 1000 pages should never take too much time so this could be overly aggressive. 100k pages could be acceptable as well. But I haven't measure that so I might be easily wrong here. So this is just my 2c > + > void mark_free_pages(struct zone *zone) > { > unsigned long pfn, max_zone_pfn; > unsigned long flags; > - unsigned int order, t; > + unsigned int order, t, page_num = 0; > struct page *page; > > if (zone_is_empty(zone)) > @@ -2548,6 +2552,9 @@ void mark_free_pages(struct zone *zone) > if (pfn_valid(pfn)) { > page = pfn_to_page(pfn); > > + if (!((page_num++) % WD_INTERVAL_PAGE)) > + touch_nmi_watchdog(); > + > if (page_zone(page) != zone) > continue; > > @@ -2555,14 +2562,19 @@ void mark_free_pages(struct zone *zone) > swsusp_unset_page_free(page); > } > > + page_num = 0; > + this part doesn't make much sense to me. You are still inside the same IRQ disabled section. So why would you want to start counting from 0 again. Not that this would make any difference in real life but the code is not logical > for_each_migratetype_order(order, t) { > list_for_each_entry(page, > &zone->free_area[order].free_list[t], lru) { > unsigned long i; > > pfn = page_to_pfn(page); > - for (i = 0; i < (1UL << order); i++) > + for (i = 0; i < (1UL << order); i++) { > + if (!((page_num++) % WD_INTERVAL_PAGE)) > + touch_nmi_watchdog(); > swsusp_set_page_free(pfn_to_page(pfn + i)); > + } > } > } > spin_unlock_irqrestore(&zone->lock, flags); > -- > 2.7.4 -- Michal Hocko SUSE Labs
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