Date: Tue, 4 Sep 2012 19:04:02 +0000 (UTC) From: Dag-Erling Smørgrav <des@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r240096 - head/sys/vm Message-ID: <201209041904.q84J42ng004100@svn.freebsd.org>
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Author: des Date: Tue Sep 4 19:04:02 2012 New Revision: 240096 URL: http://svn.freebsd.org/changeset/base/240096 Log: No memory barrier is required. This was pointed out by kib@ a while ago, but I got distracted by other matters. Modified: head/sys/vm/swap_pager.c Modified: head/sys/vm/swap_pager.c ============================================================================== --- head/sys/vm/swap_pager.c Tue Sep 4 17:29:35 2012 (r240095) +++ head/sys/vm/swap_pager.c Tue Sep 4 19:04:02 2012 (r240096) @@ -50,7 +50,7 @@ * * - on the fly reallocation of swap during putpages. The new system * does not try to keep previously allocated swap blocks for dirty - * pages. + * pages. * * - on the fly deallocation of swap * @@ -154,15 +154,21 @@ int swap_pager_avail; static int swdev_syscall_active = 0; /* serialize swap(on|off) */ static vm_ooffset_t swap_total; -SYSCTL_QUAD(_vm, OID_AUTO, swap_total, CTLFLAG_RD, &swap_total, 0, +SYSCTL_QUAD(_vm, OID_AUTO, swap_total, CTLFLAG_RD, &swap_total, 0, "Total amount of available swap storage."); static vm_ooffset_t swap_reserved; -SYSCTL_QUAD(_vm, OID_AUTO, swap_reserved, CTLFLAG_RD, &swap_reserved, 0, +SYSCTL_QUAD(_vm, OID_AUTO, swap_reserved, CTLFLAG_RD, &swap_reserved, 0, "Amount of swap storage needed to back all allocated anonymous memory."); static int overcommit = 0; -SYSCTL_INT(_vm, OID_AUTO, overcommit, CTLFLAG_RW, &overcommit, 0, +SYSCTL_INT(_vm, OID_AUTO, overcommit, CTLFLAG_RW, &overcommit, 0, "Configure virtual memory overcommit behavior. See tuning(7) " "for details."); +static unsigned long swzone; +SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, + "Actual size of swap metadata zone"); +static unsigned long swap_maxpages; +SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, + "Maximum amount of swap supported"); /* bits from overcommit */ #define SWAP_RESERVE_FORCE_ON (1 << 0) @@ -184,7 +190,7 @@ swap_reserve_by_cred(vm_ooffset_t incr, static int curfail; static struct timeval lastfail; struct uidinfo *uip; - + uip = cred->cr_ruidinfo; if (incr & PAGE_MASK) @@ -285,7 +291,7 @@ void swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) { struct uidinfo *uip; - + uip = cred->cr_ruidinfo; if (decr & PAGE_MASK) @@ -328,7 +334,7 @@ static struct sx sw_alloc_sx; SYSCTL_INT(_vm, OID_AUTO, swap_async_max, - CTLFLAG_RW, &swap_async_max, 0, "Maximum running async swap ops"); + CTLFLAG_RW, &swap_async_max, 0, "Maximum running async swap ops"); /* * "named" and "unnamed" anon region objects. Try to reduce the overhead @@ -340,7 +346,7 @@ SYSCTL_INT(_vm, OID_AUTO, swap_async_max #define NOBJLIST(handle) \ (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) -static struct mtx sw_alloc_mtx; /* protect list manipulation */ +static struct mtx sw_alloc_mtx; /* protect list manipulation */ static struct pagerlst swap_pager_object_list[NOBJLISTS]; static uma_zone_t swap_zone; static struct vm_object swap_zone_obj; @@ -419,7 +425,7 @@ swp_pager_free_nrpage(vm_page_t m) /* * SWP_SIZECHECK() - update swap_pager_full indication - * + * * update the swap_pager_almost_full indication and warn when we are * about to run out of swap space, using lowat/hiwat hysteresis. * @@ -474,7 +480,7 @@ swp_pager_hash(vm_object_t object, vm_pi /* * SWAP_PAGER_INIT() - initialize the swap pager! * - * Expected to be started from system init. NOTE: This code is run + * Expected to be started from system init. NOTE: This code is run * before much else so be careful what you depend on. Most of the VM * system has yet to be initialized at this point. */ @@ -506,7 +512,7 @@ swap_pager_init(void) void swap_pager_swap_init(void) { - int n, n2; + unsigned long n, n2; /* * Number of in-transit swap bp operations. Don't @@ -519,7 +525,7 @@ swap_pager_swap_init(void) * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are * constrained by the swap device interleave stripe size. * - * Currently we hardwire nsw_wcount_async to 4. This limit is + * Currently we hardwire nsw_wcount_async to 4. This limit is * designed to prevent other I/O from having high latencies due to * our pageout I/O. The value 4 works well for one or two active swap * devices but is probably a little low if you have more. Even so, @@ -548,11 +554,11 @@ swap_pager_swap_init(void) n = cnt.v_page_count / 2; if (maxswzone && n > maxswzone / sizeof(struct swblock)) n = maxswzone / sizeof(struct swblock); - n2 = n; swap_zone = uma_zcreate("SWAPMETA", sizeof(struct swblock), NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE | UMA_ZONE_VM); if (swap_zone == NULL) panic("failed to create swap_zone."); + n2 = n; do { if (uma_zone_set_obj(swap_zone, &swap_zone_obj, n)) break; @@ -563,12 +569,13 @@ swap_pager_swap_init(void) n -= ((n + 2) / 3); } while (n > 0); if (n2 != n) - printf("Swap zone entries reduced from %d to %d.\n", n2, n); - n2 = n; + printf("Swap zone entries reduced from %lu to %lu.\n", n2, n); + swap_maxpages = n * SWAP_META_PAGES; + swzone = n * sizeof(struct swblock); /* * Initialize our meta-data hash table. The swapper does not need to - * be quite as efficient as the VM system, so we do not use an + * be quite as efficient as the VM system, so we do not use an * oversized hash table. * * n: size of hash table, must be power of 2 @@ -654,7 +661,7 @@ swap_pager_alloc(void *handle, vm_ooffse /* * SWAP_PAGER_DEALLOC() - remove swap metadata from object * - * The swap backing for the object is destroyed. The code is + * The swap backing for the object is destroyed. The code is * designed such that we can reinstantiate it later, but this * routine is typically called only when the entire object is * about to be destroyed. @@ -679,7 +686,7 @@ swap_pager_dealloc(vm_object_t object) vm_object_pip_wait(object, "swpdea"); /* - * Free all remaining metadata. We only bother to free it from + * Free all remaining metadata. We only bother to free it from * the swap meta data. We do not attempt to free swapblk's still * associated with vm_page_t's for this object. We do not care * if paging is still in progress on some objects. @@ -748,7 +755,7 @@ swp_pager_isondev(daddr_t blk, struct sw return (blk >= sp->sw_first && blk < sp->sw_end); } - + static void swp_pager_strategy(struct buf *bp) { @@ -764,10 +771,10 @@ swp_pager_strategy(struct buf *bp) } panic("Swapdev not found"); } - + /* - * SWP_PAGER_FREESWAPSPACE() - free raw swap space + * SWP_PAGER_FREESWAPSPACE() - free raw swap space * * This routine returns the specified swap blocks back to the bitmap. * @@ -785,7 +792,7 @@ swp_pager_freeswapspace(daddr_t blk, int /* * If we are attempting to stop swapping on * this device, we don't want to mark any - * blocks free lest they be reused. + * blocks free lest they be reused. */ if ((sp->sw_flags & SW_CLOSING) == 0) { blist_free(sp->sw_blist, blk - sp->sw_first, @@ -808,8 +815,8 @@ swp_pager_freeswapspace(daddr_t blk, int * * This routine removes swapblk assignments from swap metadata. * - * The external callers of this routine typically have already destroyed - * or renamed vm_page_t's associated with this range in the object so + * The external callers of this routine typically have already destroyed + * or renamed vm_page_t's associated with this range in the object so * we should be ok. */ void @@ -823,7 +830,7 @@ swap_pager_freespace(vm_object_t object, /* * SWAP_PAGER_RESERVE() - reserve swap blocks in object * - * Assigns swap blocks to the specified range within the object. The + * Assigns swap blocks to the specified range within the object. The * swap blocks are not zerod. Any previous swap assignment is destroyed. * * Returns 0 on success, -1 on failure. @@ -869,7 +876,7 @@ swap_pager_reserve(vm_object_t object, v * * This routine is allowed to sleep. It may sleep allocating metadata * indirectly through swp_pager_meta_build() or if paging is still in - * progress on the source. + * progress on the source. * * The source object contains no vm_page_t's (which is just as well) * @@ -888,8 +895,8 @@ swap_pager_copy(vm_object_t srcobject, v VM_OBJECT_LOCK_ASSERT(dstobject, MA_OWNED); /* - * If destroysource is set, we remove the source object from the - * swap_pager internal queue now. + * If destroysource is set, we remove the source object from the + * swap_pager internal queue now. */ if (destroysource) { if (srcobject->handle != NULL) { @@ -925,7 +932,7 @@ swap_pager_copy(vm_object_t srcobject, v daddr_t srcaddr; srcaddr = swp_pager_meta_ctl( - srcobject, + srcobject, i + offset, SWM_POP ); @@ -947,7 +954,7 @@ swap_pager_copy(vm_object_t srcobject, v * Destination has valid swapblk or it is represented * by a resident page. We destroy the sourceblock. */ - + swp_pager_meta_ctl(srcobject, i + offset, SWM_FREE); } } @@ -1042,7 +1049,7 @@ swap_pager_haspage(vm_object_t object, v * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page * * This removes any associated swap backing store, whether valid or - * not, from the page. + * not, from the page. * * This routine is typically called when a page is made dirty, at * which point any associated swap can be freed. MADV_FREE also @@ -1071,7 +1078,7 @@ swap_pager_unswapped(vm_page_t m) * 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 + * 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. @@ -1101,7 +1108,7 @@ swap_pager_getpages(vm_object_t object, * 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 + * 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. @@ -1139,7 +1146,7 @@ swap_pager_getpages(vm_object_t object, } /* - * Return VM_PAGER_FAIL if we have nothing to do. Return mreq + * Return VM_PAGER_FAIL if we have nothing to do. Return mreq * still busy, but the others unbusied. */ if (blk == SWAPBLK_NONE) @@ -1234,21 +1241,21 @@ swap_pager_getpages(vm_object_t object, /* * A final note: in a low swap situation, we cannot deallocate swap * and mark a page dirty here because the caller is likely to mark - * the page clean when we return, causing the page to possibly revert + * the page clean when we return, causing the page to possibly revert * to all-zero's later. */ } /* - * swap_pager_putpages: + * swap_pager_putpages: * * Assign swap (if necessary) and initiate I/O on the specified pages. * * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects * are automatically converted to SWAP objects. * - * In a low memory situation we may block in VOP_STRATEGY(), but the new - * vm_page reservation system coupled with properly written VFS devices + * In a low memory situation we may block in VOP_STRATEGY(), but the new + * vm_page reservation system coupled with properly written VFS devices * should ensure that no low-memory deadlock occurs. This is an area * which needs work. * @@ -1269,8 +1276,8 @@ swap_pager_putpages(vm_object_t object, int n = 0; if (count && m[0]->object != object) { - panic("swap_pager_putpages: object mismatch %p/%p", - object, + panic("swap_pager_putpages: object mismatch %p/%p", + object, m[0]->object ); } @@ -1292,7 +1299,7 @@ swap_pager_putpages(vm_object_t object, /* * Step 2 * - * Update nsw parameters from swap_async_max sysctl values. + * Update nsw parameters from swap_async_max sysctl values. * Do not let the sysop crash the machine with bogus numbers. */ mtx_lock(&pbuf_mtx); @@ -1384,7 +1391,7 @@ swap_pager_putpages(vm_object_t object, vm_page_t mreq = m[i+j]; swp_pager_meta_build( - mreq->object, + mreq->object, mreq->pindex, blk + j ); @@ -1453,10 +1460,10 @@ swap_pager_putpages(vm_object_t object, * Completion routine for asynchronous reads and writes from/to swap. * Also called manually by synchronous code to finish up a bp. * - * For READ operations, the pages are VPO_BUSY'd. For WRITE operations, - * the pages are vm_page_t->busy'd. For READ operations, we VPO_BUSY - * unbusy all pages except the 'main' request page. For WRITE - * operations, we vm_page_t->busy'd unbusy all pages ( we can do this + * For READ operations, the pages are VPO_BUSY'd. For WRITE operations, + * the pages are vm_page_t->busy'd. For READ operations, we VPO_BUSY + * unbusy all pages except the 'main' request page. For WRITE + * operations, we vm_page_t->busy'd unbusy all pages ( we can do this * because we marked them all VM_PAGER_PEND on return from putpages ). * * This routine may not sleep. @@ -1475,7 +1482,7 @@ swp_pager_async_iodone(struct buf *bp) "swap_pager: I/O error - %s failed; blkno %ld," "size %ld, error %d\n", ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), - (long)bp->b_blkno, + (long)bp->b_blkno, (long)bp->b_bcount, bp->b_error ); @@ -1495,7 +1502,7 @@ swp_pager_async_iodone(struct buf *bp) * cleanup pages. If an error occurs writing to swap, we are in * very serious trouble. If it happens to be a disk error, though, * we may be able to recover by reassigning the swap later on. So - * in this case we remove the m->swapblk assignment for the page + * in this case we remove the m->swapblk assignment for the page * but do not free it in the rlist. The errornous block(s) are thus * never reallocated as swap. Redirty the page and continue. */ @@ -1508,7 +1515,7 @@ swp_pager_async_iodone(struct buf *bp) /* * If an error occurs I'd love to throw the swapblk * away without freeing it back to swapspace, so it - * can never be used again. But I can't from an + * can never be used again. But I can't from an * interrupt. */ if (bp->b_iocmd == BIO_READ) { @@ -1517,7 +1524,7 @@ swp_pager_async_iodone(struct buf *bp) * locked for the parent, but all other * pages can be freed. We still want to * wakeup the parent waiting on the page, - * though. ( also: pg_reqpage can be -1 and + * though. ( also: pg_reqpage can be -1 and * not match anything ). * * We have to wake specifically requested pages @@ -1534,7 +1541,7 @@ swp_pager_async_iodone(struct buf *bp) else vm_page_flash(m); /* - * If i == bp->b_pager.pg_reqpage, do not wake + * If i == bp->b_pager.pg_reqpage, do not wake * the page up. The caller needs to. */ } else { @@ -1551,7 +1558,7 @@ swp_pager_async_iodone(struct buf *bp) } } else if (bp->b_iocmd == BIO_READ) { /* - * NOTE: for reads, m->dirty will probably be + * NOTE: for reads, m->dirty will probably be * overridden by the original caller of getpages so * we cannot set them in order to free the underlying * swap in a low-swap situation. I don't think we'd @@ -1563,7 +1570,7 @@ swp_pager_async_iodone(struct buf *bp) * * Note that the requested page, reqpage, is left * busied, but we still have to wake it up. The - * other pages are released (unbusied) by + * other pages are released (unbusied) by * vm_page_wakeup(). */ KASSERT(!pmap_page_is_mapped(m), @@ -1577,7 +1584,7 @@ swp_pager_async_iodone(struct buf *bp) * up too because we cleared VPO_SWAPINPROG and * could be waiting for it in getpages. However, * be sure to not unbusy getpages specifically - * requested page - getpages expects it to be + * requested page - getpages expects it to be * left busy. */ if (i != bp->b_pager.pg_reqpage) { @@ -1590,7 +1597,7 @@ swp_pager_async_iodone(struct buf *bp) } else { /* * For write success, clear the dirty - * status, then finish the I/O ( which decrements the + * status, then finish the I/O ( which decrements the * busy count and possibly wakes waiter's up ). */ KASSERT(!pmap_page_is_write_mapped(m), @@ -1615,8 +1622,8 @@ swp_pager_async_iodone(struct buf *bp) VM_OBJECT_UNLOCK(object); } - /* - * swapdev_strategy() manually sets b_vp and b_bufobj before calling + /* + * swapdev_strategy() manually sets b_vp and b_bufobj before calling * bstrategy(). Set them back to NULL now we're done with it, or we'll * trigger a KASSERT in relpbuf(). */ @@ -1628,10 +1635,10 @@ swp_pager_async_iodone(struct buf *bp) * release the physical I/O buffer */ relpbuf( - bp, - ((bp->b_iocmd == BIO_READ) ? &nsw_rcount : - ((bp->b_flags & B_ASYNC) ? - &nsw_wcount_async : + bp, + ((bp->b_iocmd == BIO_READ) ? &nsw_rcount : + ((bp->b_flags & B_ASYNC) ? + &nsw_wcount_async : &nsw_wcount_sync ) ) @@ -1744,8 +1751,8 @@ restart: for (swap = swhash[i]; swap != NULL; swap = swap->swb_hnext) { vm_object_t object = swap->swb_object; vm_pindex_t pindex = swap->swb_index; - for (j = 0; j < SWAP_META_PAGES; ++j) { - if (swp_pager_isondev(swap->swb_pages[j], sp)) { + for (j = 0; j < SWAP_META_PAGES; ++j) { + if (swp_pager_isondev(swap->swb_pages[j], sp)) { /* avoid deadlock */ if (!VM_OBJECT_TRYLOCK(object)) { break; @@ -1758,7 +1765,7 @@ restart: goto restart; } } - } + } } } mtx_unlock(&swhash_mtx); @@ -1783,7 +1790,7 @@ restart: * SWAP META DATA * ************************************************************************ * - * These routines manipulate the swap metadata stored in the + * These routines manipulate the swap metadata stored in the * OBJT_SWAP object. * * Swap metadata is implemented with a global hash and not directly @@ -1821,13 +1828,13 @@ swp_pager_meta_build(vm_object_t object, mtx_lock(&sw_alloc_mtx); TAILQ_INSERT_TAIL( NOBJLIST(object->handle), - object, + object, pager_object_list ); mtx_unlock(&sw_alloc_mtx); } } - + /* * Locate hash entry. If not found create, but if we aren't adding * anything just return. If we run out of space in the map we wait @@ -1848,7 +1855,7 @@ retry: mtx_unlock(&swhash_mtx); VM_OBJECT_UNLOCK(object); if (uma_zone_exhausted(swap_zone)) { - if (atomic_cmpset_rel_int(&exhausted, 0, 1)) + if (atomic_cmpset_int(&exhausted, 0, 1)) printf("swap zone exhausted, " "increase kern.maxswzone\n"); vm_pageout_oom(VM_OOM_SWAPZ); @@ -1859,7 +1866,7 @@ retry: goto retry; } - if (atomic_cmpset_rel_int(&exhausted, 1, 0)) + if (atomic_cmpset_int(&exhausted, 1, 0)) printf("swap zone ok\n"); swap->swb_hnext = NULL; @@ -1896,10 +1903,10 @@ done: /* * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata * - * The requested range of blocks is freed, with any associated swap + * The requested range of blocks is freed, with any associated swap * returned to the swap bitmap. * - * This routine will free swap metadata structures as they are cleaned + * This routine will free swap metadata structures as they are cleaned * out. This routine does *NOT* operate on swap metadata associated * with resident pages. */ @@ -1991,14 +1998,14 @@ swp_pager_meta_free_all(vm_object_t obje * swapblk assignments in the swap meta data or in the vm_page_t. * The routine typically returns the swapblk being looked-up, or popped, * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block - * was invalid. This routine will automatically free any invalid + * was invalid. This routine will automatically free any invalid * meta-data swapblks. * * It is not possible to store invalid swapblks in the swap meta data * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking. * - * When acting on a busy resident page and paging is in progress, we - * have to wait until paging is complete but otherwise can act on the + * When acting on a busy resident page and paging is in progress, we + * have to wait until paging is complete but otherwise can act on the * busy page. * * SWM_FREE remove and free swap block from metadata @@ -2014,7 +2021,7 @@ swp_pager_meta_ctl(vm_object_t object, v VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); /* - * The meta data only exists of the object is OBJT_SWAP + * The meta data only exists of the object is OBJT_SWAP * and even then might not be allocated yet. */ if (object->type != OBJT_SWAP) @@ -2040,7 +2047,7 @@ swp_pager_meta_ctl(vm_object_t object, v uma_zfree(swap_zone, swap); --object->un_pager.swp.swp_bcount; } - } + } } } mtx_unlock(&swhash_mtx); @@ -2058,7 +2065,7 @@ struct swapon_args { }; #endif -/* +/* * MPSAFE */ /* ARGSUSED */ @@ -2153,7 +2160,7 @@ swaponsomething(struct vnode *vp, void * /* * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. * First chop nblks off to page-align it, then convert. - * + * * sw->sw_nblks is in page-sized chunks now too. */ nblks &= ~(ctodb(1) - 1); @@ -2342,12 +2349,12 @@ swapoff_all(void) struct swdevt *sp, *spt; const char *devname; int error; - + mtx_lock(&Giant); while (swdev_syscall_active) tsleep(&swdev_syscall_active, PUSER - 1, "swpoff", 0); swdev_syscall_active = 1; - + mtx_lock(&sw_dev_mtx); TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { mtx_unlock(&sw_dev_mtx); @@ -2365,7 +2372,7 @@ swapoff_all(void) mtx_lock(&sw_dev_mtx); } mtx_unlock(&sw_dev_mtx); - + swdev_syscall_active = 0; wakeup_one(&swdev_syscall_active); mtx_unlock(&Giant); @@ -2709,7 +2716,7 @@ swaponvp(struct thread *td, struct vnode } } mtx_unlock(&sw_dev_mtx); - + (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); #ifdef MAC error = mac_system_check_swapon(td->td_ucred, vp);
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