Messages in this thread | | | Date | Wed, 10 Oct 2018 22:26:41 +0530 | From | Arun KS <> | Subject | Re: [PATCH v5 1/2] memory_hotplug: Free pages as higher order |
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On 2018-10-10 21:00, Vlastimil Babka wrote: > On 10/5/18 10:10 AM, Arun KS wrote: >> When free pages are done with higher order, time spend on >> coalescing pages by buddy allocator can be reduced. With >> section size of 256MB, hot add latency of a single section >> shows improvement from 50-60 ms to less than 1 ms, hence >> improving the hot add latency by 60%. Modify external >> providers of online callback to align with the change. >> >> Signed-off-by: Arun KS <arunks@codeaurora.org> > > [...] > >> @@ -655,26 +655,44 @@ void __online_page_free(struct page *page) >> } >> EXPORT_SYMBOL_GPL(__online_page_free); >> >> -static void generic_online_page(struct page *page) >> +static int generic_online_page(struct page *page, unsigned int order) >> { >> - __online_page_set_limits(page); > > This is now not called anymore, although the xen/hv variants still do > it. The function seems empty these days, maybe remove it as a followup > cleanup? > >> - __online_page_increment_counters(page); >> - __online_page_free(page); >> + __free_pages_core(page, order); >> + totalram_pages += (1UL << order); >> +#ifdef CONFIG_HIGHMEM >> + if (PageHighMem(page)) >> + totalhigh_pages += (1UL << order); >> +#endif > > __online_page_increment_counters() would have used > adjust_managed_page_count() which would do the changes under > managed_page_count_lock. Are we safe without the lock? If yes, there > should perhaps be a comment explaining why.
Looks unsafe without managed_page_count_lock. I think better have a similar implementation of free_boot_core() in memory_hotplug.c like we had in version 1 of patch. And use adjust_managed_page_count() instead of page_zone(page)->managed_pages += nr_pages;
https://lore.kernel.org/patchwork/patch/989445/
-static void generic_online_page(struct page *page) +static int generic_online_page(struct page *page, unsigned int order) { - __online_page_set_limits(page); - __online_page_increment_counters(page); - __online_page_free(page); + unsigned long nr_pages = 1 << order; + struct page *p = page; + + for (loop = 0 ; loop < nr_pages ; loop++, p++) { + __ClearPageReserved(p); + set_page_count(p, 0); + } + + adjust_managed_page_count(page, nr_pages); + set_page_refcounted(page); + __free_pages(page, order); + + return 0; +}
Regards, Arun
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