Author: jeff Date: Tue Jan 21 00:12:57 2020 New Revision: 356936 URL: https://svnweb.freebsd.org/changeset/base/356936
Log: Move readahead and dropbehind fault functionality into a helper routine for clarity. Reviewed by: dougm, kib, markj Differential Revision: https://reviews.freebsd.org/D23282 Modified: head/sys/vm/vm_fault.c Modified: head/sys/vm/vm_fault.c ============================================================================== --- head/sys/vm/vm_fault.c Mon Jan 20 23:44:10 2020 (r356935) +++ head/sys/vm/vm_fault.c Tue Jan 21 00:12:57 2020 (r356936) @@ -120,6 +120,7 @@ __FBSDID("$FreeBSD$"); #define VM_FAULT_DONTNEED_MIN 1048576 struct faultstate { + vm_offset_t vaddr; vm_page_t m; vm_page_t m_cow; vm_object_t object; @@ -680,6 +681,59 @@ vm_fault_lock_vnode(struct faultstate *fs, bool objloc } /* + * Calculate the desired readahead. Handle drop-behind. + * + * Returns the number of readahead blocks to pass to the pager. + */ +static int +vm_fault_readahead(struct faultstate *fs) +{ + int era, nera; + u_char behavior; + + KASSERT(fs->lookup_still_valid, ("map unlocked")); + era = fs->entry->read_ahead; + behavior = vm_map_entry_behavior(fs->entry); + if (behavior == MAP_ENTRY_BEHAV_RANDOM) { + nera = 0; + } else if (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL) { + nera = VM_FAULT_READ_AHEAD_MAX; + if (fs->vaddr == fs->entry->next_read) + vm_fault_dontneed(fs, fs->vaddr, nera); + } else if (fs->vaddr == fs->entry->next_read) { + /* + * This is a sequential fault. Arithmetically + * increase the requested number of pages in + * the read-ahead window. The requested + * number of pages is "# of sequential faults + * x (read ahead min + 1) + read ahead min" + */ + nera = VM_FAULT_READ_AHEAD_MIN; + if (era > 0) { + nera += era + 1; + if (nera > VM_FAULT_READ_AHEAD_MAX) + nera = VM_FAULT_READ_AHEAD_MAX; + } + if (era == VM_FAULT_READ_AHEAD_MAX) + vm_fault_dontneed(fs, fs->vaddr, nera); + } else { + /* + * This is a non-sequential fault. + */ + nera = 0; + } + if (era != nera) { + /* + * A read lock on the map suffices to update + * the read ahead count safely. + */ + fs->entry->read_ahead = nera; + } + + return (nera); +} + +/* * Wait/Retry if the page is busy. We have to do this if the page is * either exclusive or shared busy because the vm_pager may be using * read busy for pageouts (and even pageins if it is the vnode pager), @@ -725,7 +779,7 @@ vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fa vm_offset_t e_end, e_start; vm_pindex_t retry_pindex; vm_prot_t prot, retry_prot; - int ahead, alloc_req, behind, cluster_offset, era, faultcount; + int ahead, alloc_req, behind, cluster_offset, faultcount; int nera, oom, result, rv; u_char behavior; boolean_t wired; /* Passed by reference. */ @@ -737,6 +791,7 @@ vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fa return (KERN_PROTECTION_FAILURE); fs.vp = NULL; + fs.vaddr = vaddr; faultcount = 0; nera = -1; hardfault = false; @@ -989,45 +1044,7 @@ readrest: * apply to subsequent objects in the shadow chain. */ if (nera == -1 && !P_KILLED(curproc)) { - KASSERT(fs.lookup_still_valid, ("map unlocked")); - era = fs.entry->read_ahead; - behavior = vm_map_entry_behavior(fs.entry); - if (behavior == MAP_ENTRY_BEHAV_RANDOM) { - nera = 0; - } else if (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL) { - nera = VM_FAULT_READ_AHEAD_MAX; - if (vaddr == fs.entry->next_read) - vm_fault_dontneed(&fs, vaddr, nera); - } else if (vaddr == fs.entry->next_read) { - /* - * This is a sequential fault. Arithmetically - * increase the requested number of pages in - * the read-ahead window. The requested - * number of pages is "# of sequential faults - * x (read ahead min + 1) + read ahead min" - */ - nera = VM_FAULT_READ_AHEAD_MIN; - if (era > 0) { - nera += era + 1; - if (nera > VM_FAULT_READ_AHEAD_MAX) - nera = VM_FAULT_READ_AHEAD_MAX; - } - if (era == VM_FAULT_READ_AHEAD_MAX) - vm_fault_dontneed(&fs, vaddr, nera); - } else { - /* - * This is a non-sequential fault. - */ - nera = 0; - } - if (era != nera) { - /* - * A read lock on the map suffices to update - * the read ahead count safely. - */ - fs.entry->read_ahead = nera; - } - + nera = vm_fault_readahead(&fs); /* * Prepare for unlocking the map. Save the map * entry's start and end addresses, which are used to @@ -1038,6 +1055,7 @@ readrest: */ e_start = fs.entry->start; e_end = fs.entry->end; + behavior = vm_map_entry_behavior(fs.entry); } /* _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
