Date: Sun, 2 Oct 2016 01:21:03 +0000 (UTC) From: Mark Johnston <markj@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r306575 - stable/11/sys/vm Message-ID: <201610020121.u921L3N1005368@repo.freebsd.org>
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Author: markj Date: Sun Oct 2 01:21:02 2016 New Revision: 306575 URL: https://svnweb.freebsd.org/changeset/base/306575 Log: MFC r305056, r305367: Restore swap pager readahead. Modified: stable/11/sys/vm/swap_pager.c stable/11/sys/vm/vm_page.c Directory Properties: stable/11/ (props changed) Modified: stable/11/sys/vm/swap_pager.c ============================================================================== --- stable/11/sys/vm/swap_pager.c Sun Oct 2 01:18:34 2016 (r306574) +++ stable/11/sys/vm/swap_pager.c Sun Oct 2 01:21:02 2016 (r306575) @@ -990,22 +990,21 @@ swap_pager_copy(vm_object_t srcobject, v * page and return TRUE if it does, FALSE if it doesn't. * * If TRUE, we also try to determine how much valid, contiguous backing - * store exists before and after the requested page within a reasonable - * distance. We do not try to restrict it to the swap device stripe - * (that is handled in getpages/putpages). It probably isn't worth - * doing here. + * store exists before and after the requested page. */ static boolean_t -swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after) +swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, + int *after) { - daddr_t blk0; + daddr_t blk, blk0; + int i; VM_OBJECT_ASSERT_LOCKED(object); + /* * do we have good backing store at the requested index ? */ blk0 = swp_pager_meta_ctl(object, pindex, 0); - if (blk0 == SWAPBLK_NONE) { if (before) *before = 0; @@ -1018,34 +1017,26 @@ swap_pager_haspage(vm_object_t object, v * find backwards-looking contiguous good backing store */ if (before != NULL) { - int i; - - for (i = 1; i < (SWB_NPAGES/2); ++i) { - daddr_t blk; - + for (i = 1; i < SWB_NPAGES; i++) { if (i > pindex) break; blk = swp_pager_meta_ctl(object, pindex - i, 0); if (blk != blk0 - i) break; } - *before = (i - 1); + *before = i - 1; } /* * find forward-looking contiguous good backing store */ if (after != NULL) { - int i; - - for (i = 1; i < (SWB_NPAGES/2); ++i) { - daddr_t blk; - + for (i = 1; i < SWB_NPAGES; i++) { blk = swp_pager_meta_ctl(object, pindex + i, 0); if (blk != blk0 + i) break; } - *after = (i - 1); + *after = i - 1; } return (TRUE); } @@ -1077,62 +1068,108 @@ swap_pager_unswapped(vm_page_t m) } /* - * SWAP_PAGER_GETPAGES() - bring pages in from swap - * - * Attempt to retrieve (m, count) pages from backing store, but make - * sure we retrieve at least m[reqpage]. We try to load in as large - * a chunk surrounding m[reqpage] as is contiguous in swap and which - * belongs to the same object. - * - * The code is designed for asynchronous operation and - * immediate-notification of 'reqpage' but tends not to be - * used that way. Please do not optimize-out this algorithmic - * feature, I intend to improve on it in the future. + * swap_pager_getpages() - bring pages in from swap * - * The parent has a single vm_object_pip_add() reference prior to - * calling us and we should return with the same. + * Attempt to page in the pages in array "m" of length "count". The caller + * may optionally specify that additional pages preceding and succeeding + * the specified range be paged in. The number of such pages is returned + * in the "rbehind" and "rahead" parameters, and they will be in the + * inactive queue upon return. * - * The parent has BUSY'd the pages. We should return with 'm' - * left busy, but the others adjusted. + * The pages in "m" must be busied and will remain busied upon return. */ static int swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind, int *rahead) { struct buf *bp; + vm_page_t mpred, msucc, p; + vm_pindex_t pindex; daddr_t blk; + int i, j, maxahead, maxbehind, reqcount, shift; - /* - * Calculate range to retrieve. The pages have already been assigned - * their swapblks. We require a *contiguous* range but we know it to - * not span devices. If we do not supply it, bad things - * happen. Note that blk, iblk & jblk can be SWAPBLK_NONE, but the - * loops are set up such that the case(s) are handled implicitly. - * - * The swp_*() calls must be made with the object locked. - */ - blk = swp_pager_meta_ctl(m[0]->object, m[0]->pindex, 0); + reqcount = count; - if (blk == SWAPBLK_NONE) - return (VM_PAGER_FAIL); + VM_OBJECT_WUNLOCK(object); + bp = getpbuf(&nsw_rcount); + VM_OBJECT_WLOCK(object); -#ifdef INVARIANTS - for (int i = 0; i < count; i++) - KASSERT(blk + i == - swp_pager_meta_ctl(m[i]->object, m[i]->pindex, 0), - ("%s: range is not contiguous", __func__)); -#endif + if (!swap_pager_haspage(object, m[0]->pindex, &maxbehind, &maxahead)) { + relpbuf(bp, &nsw_rcount); + return (VM_PAGER_FAIL); + } /* - * Getpbuf() can sleep. + * Clip the readahead and readbehind ranges to exclude resident pages. */ - VM_OBJECT_WUNLOCK(object); + if (rahead != NULL) { + KASSERT(reqcount - 1 <= maxahead, + ("page count %d extends beyond swap block", reqcount)); + *rahead = imin(*rahead, maxahead - (reqcount - 1)); + pindex = m[reqcount - 1]->pindex; + msucc = TAILQ_NEXT(m[reqcount - 1], listq); + if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) + *rahead = msucc->pindex - pindex - 1; + } + if (rbehind != NULL) { + *rbehind = imin(*rbehind, maxbehind); + pindex = m[0]->pindex; + mpred = TAILQ_PREV(m[0], pglist, listq); + if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) + *rbehind = pindex - mpred->pindex - 1; + } + /* - * Get a swap buffer header to perform the IO - */ - bp = getpbuf(&nsw_rcount); - bp->b_flags |= B_PAGING; + * Allocate readahead and readbehind pages. + */ + shift = rbehind != NULL ? *rbehind : 0; + if (shift != 0) { + for (i = 1; i <= shift; i++) { + p = vm_page_alloc(object, m[0]->pindex - i, + VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); + if (p == NULL) { + /* Shift allocated pages to the left. */ + for (j = 0; j < i - 1; j++) + bp->b_pages[j] = + bp->b_pages[j + shift - i + 1]; + break; + } + bp->b_pages[shift - i] = p; + } + shift = i - 1; + *rbehind = shift; + } + for (i = 0; i < reqcount; i++) + bp->b_pages[i + shift] = m[i]; + if (rahead != NULL) { + for (i = 0; i < *rahead; i++) { + p = vm_page_alloc(object, + m[reqcount - 1]->pindex + i + 1, + VM_ALLOC_NORMAL | VM_ALLOC_IFNOTCACHED); + if (p == NULL) + break; + bp->b_pages[shift + reqcount + i] = p; + } + *rahead = i; + } + if (rbehind != NULL) + count += *rbehind; + if (rahead != NULL) + count += *rahead; + + vm_object_pip_add(object, count); + + for (i = 0; i < count; i++) + bp->b_pages[i]->oflags |= VPO_SWAPINPROG; + + pindex = bp->b_pages[0]->pindex; + blk = swp_pager_meta_ctl(object, pindex, 0); + KASSERT(blk != SWAPBLK_NONE, + ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); + VM_OBJECT_WUNLOCK(object); + + bp->b_flags |= B_PAGING; bp->b_iocmd = BIO_READ; bp->b_iodone = swp_pager_async_iodone; bp->b_rcred = crhold(thread0.td_ucred); @@ -1141,22 +1178,11 @@ swap_pager_getpages(vm_object_t object, bp->b_bcount = PAGE_SIZE * count; bp->b_bufsize = PAGE_SIZE * count; bp->b_npages = count; - - VM_OBJECT_WLOCK(object); - for (int i = 0; i < count; i++) { - bp->b_pages[i] = m[i]; - m[i]->oflags |= VPO_SWAPINPROG; - } + bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; + bp->b_pgafter = rahead != NULL ? *rahead : 0; PCPU_INC(cnt.v_swapin); - PCPU_ADD(cnt.v_swappgsin, bp->b_npages); - - /* - * We still hold the lock on mreq, and our automatic completion routine - * does not remove it. - */ - vm_object_pip_add(object, bp->b_npages); - VM_OBJECT_WUNLOCK(object); + PCPU_ADD(cnt.v_swappgsin, count); /* * perform the I/O. NOTE!!! bp cannot be considered valid after @@ -1173,9 +1199,9 @@ swap_pager_getpages(vm_object_t object, swp_pager_strategy(bp); /* - * wait for the page we want to complete. VPO_SWAPINPROG is always + * Wait for the pages we want to complete. VPO_SWAPINPROG is always * cleared on completion. If an I/O error occurs, SWAPBLK_NONE - * is set in the meta-data. + * is set in the metadata for each page in the request. */ VM_OBJECT_WLOCK(object); while ((m[0]->oflags & VPO_SWAPINPROG) != 0) { @@ -1192,15 +1218,10 @@ swap_pager_getpages(vm_object_t object, /* * If we had an unrecoverable read error pages will not be valid. */ - for (int i = 0; i < count; i++) + for (i = 0; i < reqcount; i++) if (m[i]->valid != VM_PAGE_BITS_ALL) return (VM_PAGER_ERROR); - if (rbehind) - *rbehind = 0; - if (rahead) - *rahead = 0; - return (VM_PAGER_OK); /* @@ -1518,7 +1539,11 @@ swp_pager_async_iodone(struct buf *bp) ("swp_pager_async_iodone: page %p is mapped", m)); KASSERT(m->dirty == 0, ("swp_pager_async_iodone: page %p is dirty", m)); + m->valid = VM_PAGE_BITS_ALL; + if (i < bp->b_pgbefore || + i >= bp->b_npages - bp->b_pgafter) + vm_page_readahead_finish(m); } else { /* * For write success, clear the dirty Modified: stable/11/sys/vm/vm_page.c ============================================================================== --- stable/11/sys/vm/vm_page.c Sun Oct 2 01:18:34 2016 (r306574) +++ stable/11/sys/vm/vm_page.c Sun Oct 2 01:21:02 2016 (r306575) @@ -1030,8 +1030,8 @@ vm_page_free_zero(vm_page_t m) } /* - * Unbusy and handle the page queueing for a page from the VOP_GETPAGES() - * array which was optionally read ahead or behind. + * Unbusy and handle the page queueing for a page from a getpages request that + * was optionally read ahead or behind. */ void vm_page_readahead_finish(vm_page_t m)
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