On 2 Sep 2020, at 16:29, Randy Dunlap wrote: > On 9/2/20 11:06 AM, Zi Yan wrote: >> From: Zi Yan <[email protected]> >> >> When depositing page table pages for 1GB THPs, we need 512 PTE pages + >> 1 PMD page. Instead of counting and depositing 513 pages, we can use the >> PMD page as a leader page and chain the rest 512 PTE pages with ->lru. >> This, however, prevents us depositing PMD pages with ->lru, which is >> currently used by depositing PTE pages for 2MB THPs. So add a new >> pagechain container for PMD pages. >> >> Signed-off-by: Zi Yan <[email protected]> >> --- >> include/linux/pagechain.h | 73 +++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 73 insertions(+) >> create mode 100644 include/linux/pagechain.h >> >> diff --git a/include/linux/pagechain.h b/include/linux/pagechain.h >> new file mode 100644 >> index 000000000000..be536142b413 >> --- /dev/null >> +++ b/include/linux/pagechain.h >> @@ -0,0 +1,73 @@ >> +/* SPDX-License-Identifier: GPL-2.0 */ >> +/* >> + * include/linux/pagechain.h >> + * >> + * In many places it is efficient to batch an operation up against multiple >> + * pages. A pagechain is a multipage container which is used for that. >> + */ >> + >> +#ifndef _LINUX_PAGECHAIN_H >> +#define _LINUX_PAGECHAIN_H >> + >> +#include <linux/slab.h> >> + >> +/* 14 pointers + two long's align the pagechain structure to a power of two >> */ >> +#define PAGECHAIN_SIZE 13 > > OK, I'll bite. I see neither 14 pointers nor 2 longs below. > Is the comment out of date or am I just confuzed? > > Update: struct list_head is 2 pointers, so I see 15 pointers & one unsigned > int. > Where are the 2 longs?
My bad. Will change this to:
/* 15 pointers + one long align the pagechain structure to a power of two */
#define PAGECHAIN_SIZE 13
struct page;
struct pagechain {
struct list_head list;
unsigned long nr;
struct page *pages[PAGECHAIN_SIZE];
};
Thanks for checking.
—
Best Regards,
Yan Zi
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