[v7,2/9] mm: Place unscrubbed pages at the end of pagelist

Message ID	1502228707-31883-3-git-send-email-boris.ostrovsky@oracle.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <xen-devel-bounces@lists.xen.org> From: Boris Ostrovsky <boris.ostrovsky@oracle.com> To: xen-devel@lists.xen.org Date: Tue, 8 Aug 2017 17:45:00 -0400 Message-Id: <1502228707-31883-3-git-send-email-boris.ostrovsky@oracle.com> In-Reply-To: <1502228707-31883-1-git-send-email-boris.ostrovsky@oracle.com> References: <1502228707-31883-1-git-send-email-boris.ostrovsky@oracle.com> Cc: sstabellini@kernel.org, wei.liu2@citrix.com, George.Dunlap@eu.citrix.com, andrew.cooper3@citrix.com, ian.jackson@eu.citrix.com, tim@xen.org, julien.grall@arm.com, jbeulich@suse.com, Boris Ostrovsky <boris.ostrovsky@oracle.com> Subject: [Xen-devel] [PATCH v7 2/9] mm: Place unscrubbed pages at the end of pagelist Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" <xen-devel-bounces@lists.xen.org>

diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c index 330f8ed..b857a44 100644 --- a/xen/common/page_alloc.c +++ b/xen/common/page_alloc.c @@ -383,6 +383,8 @@ typedef struct page_list_head heap_by_zone_and_order_t[NR_ZONES][MAX_ORDER+1]; static heap_by_zone_and_order_t *_heap[MAX_NUMNODES]; #define heap(node, zone, order) ((*_heap[node])[zone][order]) +static unsigned long node_need_scrub[MAX_NUMNODES]; + static unsigned long *avail[MAX_NUMNODES]; static long total_avail_pages; @@ -678,13 +680,30 @@ static void check_low_mem_virq(void) } } +/* Pages that need a scrub are added to tail, otherwise to head. */ +static void page_list_add_scrub(struct page_info *pg, unsigned int node, + unsigned int zone, unsigned int order, + unsigned int first_dirty) +{ + PFN_ORDER(pg) = order; + pg->u.free.first_dirty = first_dirty; + + if ( first_dirty != INVALID_DIRTY_IDX ) + { + ASSERT(first_dirty < (1U << order)); + page_list_add_tail(pg, &heap(node, zone, order)); + } + else + page_list_add(pg, &heap(node, zone, order)); +} + /* Allocate 2^@order contiguous pages. */ static struct page_info *alloc_heap_pages( unsigned int zone_lo, unsigned int zone_hi, unsigned int order, unsigned int memflags, struct domain *d) { - unsigned int i, j, zone = 0, nodemask_retry = 0; + unsigned int i, j, zone = 0, nodemask_retry = 0, first_dirty; nodeid_t first_node, node = MEMF_get_node(memflags), req_node = node; unsigned long request = 1UL << order; struct page_info *pg; @@ -798,12 +817,26 @@ static struct page_info *alloc_heap_pages( return NULL; found: + + first_dirty = pg->u.free.first_dirty; + /* We may have to halve the chunk a number of times. */ while ( j != order ) { - PFN_ORDER(pg) = --j; - page_list_add_tail(pg, &heap(node, zone, j)); - pg += 1 << j; + j--; + page_list_add_scrub(pg, node, zone, j, + (1U << j) > first_dirty ? + first_dirty : INVALID_DIRTY_IDX); + pg += 1U << j; + + if ( first_dirty != INVALID_DIRTY_IDX ) + { + /* Adjust first_dirty */ + if ( first_dirty >= 1U << j ) + first_dirty -= 1U << j; + else + first_dirty = 0; /* We've moved past original first_dirty */ + } } ASSERT(avail[node][zone] >= request); @@ -850,12 +883,20 @@ static int reserve_offlined_page(struct page_info *head) unsigned int node = phys_to_nid(page_to_maddr(head)); int zone = page_to_zone(head), i, head_order = PFN_ORDER(head), count = 0; struct page_info *cur_head; - int cur_order; + unsigned int cur_order, first_dirty; ASSERT(spin_is_locked(&heap_lock)); cur_head = head; + /* + * We may break the buddy so let's mark the head as clean. Then, when + * merging chunks back into the heap, we will see whether the chunk has + * unscrubbed pages and set its first_dirty properly. + */ + first_dirty = head->u.free.first_dirty; + head->u.free.first_dirty = INVALID_DIRTY_IDX; + page_list_del(head, &heap(node, zone, head_order)); while ( cur_head < (head + (1 << head_order)) ) @@ -866,6 +907,8 @@ static int reserve_offlined_page(struct page_info *head) if ( page_state_is(cur_head, offlined) ) { cur_head++; + if ( first_dirty != INVALID_DIRTY_IDX && first_dirty ) + first_dirty--; continue; } @@ -892,9 +935,20 @@ static int reserve_offlined_page(struct page_info *head) { merge: /* We don't consider merging outside the head_order. */ - page_list_add_tail(cur_head, &heap(node, zone, cur_order)); - PFN_ORDER(cur_head) = cur_order; + page_list_add_scrub(cur_head, node, zone, cur_order, + (1U << cur_order) > first_dirty ? + first_dirty : INVALID_DIRTY_IDX); cur_head += (1 << cur_order); + + /* Adjust first_dirty if needed. */ + if ( first_dirty != INVALID_DIRTY_IDX ) + { + if ( first_dirty >= 1U << cur_order ) + first_dirty -= 1U << cur_order; + else + first_dirty = 0; + } + break; } } @@ -919,9 +973,53 @@ static int reserve_offlined_page(struct page_info *head) return count; } +static void scrub_free_pages(unsigned int node) +{ + struct page_info *pg; + unsigned int zone; + + ASSERT(spin_is_locked(&heap_lock)); + + if ( !node_need_scrub[node] ) + return; + + for ( zone = 0; zone < NR_ZONES; zone++ ) + { + unsigned int order = MAX_ORDER; + + do { + while ( !page_list_empty(&heap(node, zone, order)) ) + { + unsigned int i; + + /* Unscrubbed pages are always at the end of the list. */ + pg = page_list_last(&heap(node, zone, order)); + if ( pg->u.free.first_dirty == INVALID_DIRTY_IDX ) + break; + + for ( i = pg->u.free.first_dirty; i < (1U << order); i++) + { + if ( test_bit(_PGC_need_scrub, &pg[i].count_info) ) + { + scrub_one_page(&pg[i]); + pg[i].count_info &= ~PGC_need_scrub; + node_need_scrub[node]--; + } + } + + page_list_del(pg, &heap(node, zone, order)); + page_list_add_scrub(pg, node, zone, order, INVALID_DIRTY_IDX); + + if ( node_need_scrub[node] == 0 ) + return; + } + } while ( order-- != 0 ); + } +} + /* Free 2^@order set of pages. */ static void free_heap_pages( - struct page_info *pg, unsigned int order) + struct page_info *pg, unsigned int order, bool need_scrub) { unsigned long mask, mfn = page_to_mfn(pg); unsigned int i, node = phys_to_nid(page_to_maddr(pg)), tainted = 0; @@ -961,10 +1059,20 @@ static void free_heap_pages( /* This page is not a guest frame any more. */ page_set_owner(&pg[i], NULL); /* set_gpfn_from_mfn snoops pg owner */ set_gpfn_from_mfn(mfn + i, INVALID_M2P_ENTRY); + + if ( need_scrub ) + pg[i].count_info |= PGC_need_scrub; } avail[node][zone] += 1 << order; total_avail_pages += 1 << order; + if ( need_scrub ) + { + node_need_scrub[node] += 1 << order; + pg->u.free.first_dirty = 0; + } + else + pg->u.free.first_dirty = INVALID_DIRTY_IDX; if ( tmem_enabled() ) midsize_alloc_zone_pages = max( @@ -988,6 +1096,12 @@ static void free_heap_pages( page_list_del(predecessor, &heap(node, zone, order)); + /* Keep predecessor's first_dirty if it is already set. */ + if ( predecessor->u.free.first_dirty == INVALID_DIRTY_IDX && + pg->u.free.first_dirty != INVALID_DIRTY_IDX ) + predecessor->u.free.first_dirty = (1U << order) + + pg->u.free.first_dirty; + pg = predecessor; } else @@ -1007,12 +1121,14 @@ static void free_heap_pages( order++; } - PFN_ORDER(pg) = order; - page_list_add_tail(pg, &heap(node, zone, order)); + page_list_add_scrub(pg, node, zone, order, pg->u.free.first_dirty); if ( tainted ) reserve_offlined_page(pg); + if ( need_scrub ) + scrub_free_pages(node); + spin_unlock(&heap_lock); } @@ -1233,7 +1349,7 @@ unsigned int online_page(unsigned long mfn, uint32_t *status) spin_unlock(&heap_lock); if ( (y & PGC_state) == PGC_state_offlined ) - free_heap_pages(pg, 0); + free_heap_pages(pg, 0, false); return ret; } @@ -1276,6 +1392,8 @@ static void init_heap_pages( { unsigned long i; + BUILD_BUG_ON(sizeof(pg->u) != sizeof(unsigned long)); + for ( i = 0; i < nr_pages; i++ ) { unsigned int nid = phys_to_nid(page_to_maddr(pg+i)); @@ -1302,7 +1420,7 @@ static void init_heap_pages( nr_pages -= n; } - free_heap_pages(pg+i, 0); + free_heap_pages(pg + i, 0, false); } } @@ -1629,7 +1747,7 @@ void free_xenheap_pages(void *v, unsigned int order) memguard_guard_range(v, 1 << (order + PAGE_SHIFT)); - free_heap_pages(virt_to_page(v), order); + free_heap_pages(virt_to_page(v), order, false); } #else @@ -1683,12 +1801,9 @@ void free_xenheap_pages(void *v, unsigned int order) pg = virt_to_page(v); for ( i = 0; i < (1u << order); i++ ) - { - scrub_one_page(&pg[i]); pg[i].count_info &= ~PGC_xen_heap; - } - free_heap_pages(pg, order); + free_heap_pages(pg, order, true); } #endif @@ -1797,7 +1912,7 @@ struct page_info *alloc_domheap_pages( if ( d && !(memflags & MEMF_no_owner) && assign_pages(d, pg, order, memflags) ) { - free_heap_pages(pg, order); + free_heap_pages(pg, order, false); return NULL; } @@ -1865,11 +1980,7 @@ void free_domheap_pages(struct page_info *pg, unsigned int order) scrub = 1; } - if ( unlikely(scrub) ) - for ( i = 0; i < (1 << order); i++ ) - scrub_one_page(&pg[i]); - - free_heap_pages(pg, order); + free_heap_pages(pg, order, scrub); } if ( drop_dom_ref ) diff --git a/xen/include/asm-arm/mm.h b/xen/include/asm-arm/mm.h index ef84b72..572337c 100644 --- a/xen/include/asm-arm/mm.h +++ b/xen/include/asm-arm/mm.h @@ -44,7 +44,16 @@ struct page_info /* Page is on a free list: ((count_info & PGC_count_mask) == 0). */ struct { /* Do TLBs need flushing for safety before next page use? */ - bool_t need_tlbflush; + bool need_tlbflush:1; + + /* + * Index of the first *possibly* unscrubbed page in the buddy. + * One more bit than maximum possible order to accommodate + * INVALID_DIRTY_IDX. + */ +#define INVALID_DIRTY_IDX ((1UL << (MAX_ORDER + 1)) - 1) + unsigned long first_dirty:MAX_ORDER + 1; + } free; } u; @@ -107,6 +116,13 @@ struct page_info #define PGC_count_width PG_shift(9) #define PGC_count_mask ((1UL<<PGC_count_width)-1) +/* + * Page needs to be scrubbed. Since this bit can only be set on a page that is + * free (i.e. in PGC_state_free) we can reuse PGC_allocated bit. + */ +#define _PGC_need_scrub _PGC_allocated +#define PGC_need_scrub PGC_allocated + extern mfn_t xenheap_mfn_start, xenheap_mfn_end; extern vaddr_t xenheap_virt_end; #ifdef CONFIG_ARM_64 diff --git a/xen/include/asm-x86/mm.h b/xen/include/asm-x86/mm.h index 2bf3f33..07dc963 100644 --- a/xen/include/asm-x86/mm.h +++ b/xen/include/asm-x86/mm.h @@ -88,7 +88,15 @@ struct page_info /* Page is on a free list: ((count_info & PGC_count_mask) == 0). */ struct { /* Do TLBs need flushing for safety before next page use? */ - bool_t need_tlbflush; + bool need_tlbflush:1; + + /* + * Index of the first *possibly* unscrubbed page in the buddy. + * One more bit than maximum possible order to accommodate + * INVALID_DIRTY_IDX. + */ +#define INVALID_DIRTY_IDX ((1UL << (MAX_ORDER + 1)) - 1) + unsigned long first_dirty:MAX_ORDER + 1; } free; } u; @@ -233,6 +241,13 @@ struct page_info #define PGC_count_width PG_shift(9) #define PGC_count_mask ((1UL<<PGC_count_width)-1) +/* + * Page needs to be scrubbed. Since this bit can only be set on a page that is + * free (i.e. in PGC_state_free) we can reuse PGC_allocated bit. + */ +#define _PGC_need_scrub _PGC_allocated +#define PGC_need_scrub PGC_allocated + #define is_xen_heap_page(page) ((page)->count_info & PGC_xen_heap) #define is_xen_heap_mfn(mfn) \ (__mfn_valid(mfn) && is_xen_heap_page(__mfn_to_page(mfn)))

[v7,2/9] mm: Place unscrubbed pages at the end of pagelist

Commit Message

Comments

Patch