Date: Tue, 6 Dec 2011 19:04:45 +0000 (UTC) From: Attilio Rao <attilio@FreeBSD.org> To: src-committers@freebsd.org, svn-src-user@freebsd.org Subject: svn commit: r228312 - user/attilio/vmcontention/sys/vm Message-ID: <201112061904.pB6J4jTO004323@svn.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: attilio Date: Tue Dec 6 19:04:45 2011 New Revision: 228312 URL: http://svn.freebsd.org/changeset/base/228312 Log: - Make rn_count 32-bits as it will naturally pad for 32-bit arches - Avoid to use atomic to manipulate it at level0 because it seems unneeded and introduces a bug on big-endian architectures where only the top half (2 bits) of the double-words are written (as sparc64, for example, doesn't support atomics at 16-bits) heading to a wrong handling of rn_count. Reported by: flo, andreast Found by: marius No answer by: jeff Modified: user/attilio/vmcontention/sys/vm/vm_radix.c user/attilio/vmcontention/sys/vm/vm_radix.h Modified: user/attilio/vmcontention/sys/vm/vm_radix.c ============================================================================== --- user/attilio/vmcontention/sys/vm/vm_radix.c Tue Dec 6 18:01:09 2011 (r228311) +++ user/attilio/vmcontention/sys/vm/vm_radix.c Tue Dec 6 19:04:45 2011 (r228312) @@ -344,7 +344,7 @@ vm_radix_insert(struct vm_radix *rtree, rnode->rn_child[slot], (u_long)index)); val = (void *)((uintptr_t)val | VM_RADIX_BLACK); rnode->rn_child[slot] = val; - atomic_add_int((volatile int *)&rnode->rn_count, 1); + rnode->rn_count++; CTR6(KTR_VM, "insert: tree %p, index %ju, level %d, slot %d, rnode %p, count %u", rtree, (uintmax_t)index, level, slot, rnode, rnode->rn_count); @@ -681,14 +681,7 @@ vm_radix_remove(struct vm_radix *rtree, (rnode != NULL) ? rnode->rn_child[slot] : NULL, (rnode != NULL) ? rnode->rn_count : 0); rnode->rn_child[slot] = NULL; - /* - * Use atomics for the last level since red and black - * will both adjust it. - */ - if (level == 0) - atomic_add_int((volatile int *)&rnode->rn_count, -1); - else - rnode->rn_count--; + rnode->rn_count--; /* * Only allow black removes to prune the tree. */ Modified: user/attilio/vmcontention/sys/vm/vm_radix.h ============================================================================== --- user/attilio/vmcontention/sys/vm/vm_radix.h Tue Dec 6 18:01:09 2011 (r228311) +++ user/attilio/vmcontention/sys/vm/vm_radix.h Tue Dec 6 19:04:45 2011 (r228312) @@ -61,8 +61,8 @@ struct vm_radix { CTASSERT(VM_RADIX_HEIGHT >= VM_RADIX_LIMIT); struct vm_radix_node { - void *rn_child[VM_RADIX_COUNT]; /* Child nodes. */ - volatile uint16_t rn_count; /* Valid children. */ + void *rn_child[VM_RADIX_COUNT]; /* Child nodes. */ + uint32_t rn_count; /* Valid children. */ }; void vm_radix_init(void);
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201112061904.pB6J4jTO004323>