Messages in this thread Patch in this message | | | Date | Thu, 23 Nov 2006 16:49:40 +0000 | Subject | [PATCH 2/4] lumpy cleanup a missplaced comment and simplify some code | From | Andy Whitcroft <> |
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lumpy: cleanup a missplaced comment and simplify some code
Move the comment for isolate_lru_pages() back to its function and comment the new function. Add some running commentry on the area scan. Cleanup the indentation on switch to match the majority view in mm/*. Finally, clarify the boundary pfn calculations.
Signed-off-by: Andy Whitcroft <apw@shadowen.org> --- diff --git a/mm/vmscan.c b/mm/vmscan.c index 4645a3f..3b6ef79 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -609,21 +609,14 @@ keep: } /* - * zone->lru_lock is heavily contended. Some of the functions that - * shrink the lists perform better by taking out a batch of pages - * and working on them outside the LRU lock. + * Attempt to remove the specified page from its LRU. Only take this + * page if it is of the appropriate PageActive status. Pages which + * are being freed elsewhere are also ignored. * - * For pagecache intensive workloads, this function is the hottest - * spot in the kernel (apart from copy_*_user functions). - * - * Appropriate locks must be held before calling this function. + * @page: page to consider + * @active: active/inactive flag only take pages of this type * - * @nr_to_scan: The number of pages to look through on the list. - * @src: The LRU list to pull pages off. - * @dst: The temp list to put pages on to. - * @scanned: The number of pages that were scanned. - * - * returns how many pages were moved onto *@dst. + * returns 0 on success, -ve errno on failure. */ int __isolate_lru_page(struct page *page, int active) { @@ -645,6 +638,23 @@ int __isolate_lru_page(struct page *page return ret; } +/* + * zone->lru_lock is heavily contended. Some of the functions that + * shrink the lists perform better by taking out a batch of pages + * and working on them outside the LRU lock. + * + * For pagecache intensive workloads, this function is the hottest + * spot in the kernel (apart from copy_*_user functions). + * + * Appropriate locks must be held before calling this function. + * + * @nr_to_scan: The number of pages to look through on the list. + * @src: The LRU list to pull pages off. + * @dst: The temp list to put pages on to. + * @scanned: The number of pages that were scanned. + * + * returns how many pages were moved onto *@dst. + */ static unsigned long isolate_lru_pages(unsigned long nr_to_scan, struct list_head *src, struct list_head *dst, unsigned long *scanned, int order) @@ -662,26 +672,31 @@ static unsigned long isolate_lru_pages(u active = PageActive(page); switch (__isolate_lru_page(page, active)) { - case 0: - list_move(&page->lru, dst); - nr_taken++; - break; + case 0: + list_move(&page->lru, dst); + nr_taken++; + break; - case -EBUSY: - /* else it is being freed elsewhere */ - list_move(&page->lru, src); - continue; + case -EBUSY: + /* else it is being freed elsewhere */ + list_move(&page->lru, src); + continue; - default: - BUG(); + default: + BUG(); } if (!order) continue; - page_pfn = pfn = __page_to_pfn(page); - end_pfn = pfn &= ~((1 << order) - 1); - end_pfn += 1 << order; + /* + * Attempt to take all pages in the order aligned region + * surrounding the tag page. Only take those pages of + * the same active state as that tag page. + */ + page_pfn = __page_to_pfn(page); + pfn = page_pfn & ~((1 << order) - 1); + end_pfn = pfn + (1 << order); for (; pfn < end_pfn; pfn++) { if (unlikely(pfn == page_pfn)) continue; @@ -691,17 +706,16 @@ static unsigned long isolate_lru_pages(u scan++; tmp = __pfn_to_page(pfn); switch (__isolate_lru_page(tmp, active)) { - case 0: - list_move(&tmp->lru, dst); - nr_taken++; - continue; - - case -EBUSY: - /* else it is being freed elsewhere */ - list_move(&tmp->lru, src); - default: - break; + case 0: + list_move(&tmp->lru, dst); + nr_taken++; + continue; + case -EBUSY: + /* else it is being freed elsewhere */ + list_move(&tmp->lru, src); + default: + break; } break; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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