Date: Sat, 30 Sep 2017 18:23:45 +0000 (UTC) From: Mateusz Guzik <mjg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r324127 - head/sys/fs/tmpfs Message-ID: <201709301823.v8UINjDY082911@repo.freebsd.org>
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Author: mjg Date: Sat Sep 30 18:23:45 2017 New Revision: 324127 URL: https://svnweb.freebsd.org/changeset/base/324127 Log: tmpfs: skip zero-sized page count updates Such updates consisted of vast majority of modificiations, especially in tmpfs_reg_resize. For the case where page count did no change and the size grew we only need to update tn_size. Use this fact to avoid vm object lock/relock. MFC after: 1 week Modified: head/sys/fs/tmpfs/tmpfs_subr.c Modified: head/sys/fs/tmpfs/tmpfs_subr.c ============================================================================== --- head/sys/fs/tmpfs/tmpfs_subr.c Sat Sep 30 18:07:46 2017 (r324126) +++ head/sys/fs/tmpfs/tmpfs_subr.c Sat Sep 30 18:23:45 2017 (r324127) @@ -350,7 +350,8 @@ tmpfs_free_node_locked(struct tmpfs_mount *tmp, struct case VREG: uobj = node->tn_reg.tn_aobj; if (uobj != NULL) { - atomic_subtract_long(&tmp->tm_pages_used, uobj->size); + if (uobj->size != 0) + atomic_subtract_long(&tmp->tm_pages_used, uobj->size); KASSERT((uobj->flags & OBJ_TMPFS) == 0, ("leaked OBJ_TMPFS node %p vm_obj %p", node, uobj)); vm_object_deallocate(uobj); @@ -1375,6 +1376,12 @@ tmpfs_reg_resize(struct vnode *vp, off_t newsize, bool oldpages = OFF_TO_IDX(oldsize + PAGE_MASK); MPASS(oldpages == uobj->size); newpages = OFF_TO_IDX(newsize + PAGE_MASK); + + if (__predict_true(newpages == oldpages && newsize >= oldsize)) { + node->tn_size = newsize; + return (0); + } + if (newpages > oldpages && tmpfs_pages_check_avail(tmp, newpages - oldpages) == 0) return (ENOSPC);
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