* Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> wrote: > During memory hotplugging we traverse struct pages three times: > > 1. memset(0) in sparse_add_one_section() > 2. loop in __add_section() to set do: set_page_node(page, nid); and > SetPageReserved(page); > 3. loop in memmap_init_zone() to call __init_single_pfn() > > This patch remove the first two loops, and leaves only loop 3. All struct > pages are initialized in one place, the same as it is done during boot. s/remove /removes > The benefits: > - We improve the memory hotplug performance because we are not evicting > cache several times and also reduce loop branching overheads. s/We improve the memory hotplug performance /We improve memory hotplug performance s/not evicting cache several times /not evicting the cache several times s/overheads /overhead > - Remove condition from hotpath in __init_single_pfn(), that was added in > order to fix the problem that was reported by Bharata in the above email > thread, thus also improve the performance during normal boot. s/improve the performance /improve performance > - Make memory hotplug more similar to boot memory initialization path > because we zero and initialize struct pages only in one function. s/more similar to boot memory initialization path /more similar to the boot memory initialization path > - Simplifies memory hotplug strut page initialization code, and thus > enables future improvements, such as multi-threading the initialization > of struct pages in order to improve the hotplug performance even further > on larger machines. s/strut /struct s/to improve the hotplug performance even further /to improve hotplug performance even further > @@ -260,21 +260,12 @@ static int __meminit __add_section(int nid, unsigned long phys_start_pfn, > return ret; > > /* > - * Make all the pages reserved so that nobody will stumble over half > - * initialized state. > - * FIXME: We also have to associate it with a node because page_to_nid > - * relies on having page with the proper node. > + * The first page in every section holds node id, this is because we > + * will need it in online_pages(). s/holds node id /holds the node id > +#ifdef CONFIG_DEBUG_VM > + /* > + * poison uninitialized struct pages in order to catch invalid flags > + * combinations. Please capitalize sentences properly. > + */ > + memset(memmap, PAGE_POISON_PATTERN, > + sizeof(struct page) * PAGES_PER_SECTION); > +#endif I'd suggest writing this into a single line: memset(memmap, PAGE_POISON_PATTERN, sizeof(struct page)*PAGES_PER_SECTION); (And ignore any checkpatch whinging - the line break didn't make it more readable.) With those details fixed, and assuming that this patch was tested: Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx> Thanks, Ingo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
