On Tue, Jan 23, 2001 at 11:03:35PM -0000, eeh@netbsd.org wrote:

 > No; but it really improves interactive performance
 > if you do `dd if=/dev/null of=/tmp/foo'.

Indeed.  I also tried a similar change, but to the case in ubc_alloc()
where a window is recycled.  That shows similar improvement, but not
as much in the dd example above (BTW -- /dev/zero :-)

...but my version also has less TLB invalidation traffic (the recycle
case of ubc_alloc() already does a pmap_remove() for the UBC window, so
the page deactication isn't as big of an expense there).

-- 
        -- Jason R. Thorpe <thorpej@zembu.com>

Index: uvm_bio.c
===================================================================
RCS file: /cvsroot/syssrc/sys/uvm/uvm_bio.c,v
retrieving revision 1.6
diff -c -r1.6 uvm_bio.c
*** uvm_bio.c	2000/12/27 09:01:45	1.6
--- uvm_bio.c	2001/01/23 23:20:19
***************
*** 117,122 ****
--- 117,134 ----
  #endif
  
  /*
+  * If true, this causes UBC pages to be placed on the inactive list
+  * rather than remain on the active list after being released.
+  */
+ boolean_t ubc_release_deactivate = FALSE;
+ 
+ /*
+  * If true, this causes UBC pages to be placed on the inactive list
+  * rather than remain on the active list after a UBC window is reused.
+  */
+ boolean_t ubc_recycle_deactivate = TRUE;
+ 
+ /*
   * ubc_init
   *
   * init pager private data structures.
***************
*** 400,405 ****
--- 412,465 ----
  
  		if (umap->uobj != NULL) {
  			LIST_REMOVE(umap, hash);
+ 
+ 			if (ubc_recycle_deactivate) {
+ 				/*
+ 				 * Deactivate the pages.  This saves the
+ 				 * pagedaemon from having to scan them,
+ 				 * and also makes it more likely that
+ 				 * these will be thrown away first, rather
+ 				 * than some random process's working set.
+ 				 */
+ 				struct uvm_object *oobj = umap->uobj;
+ 				vm_page_t pg;
+ 				voff_t objoff;
+ 
+ 				/*
+ 				 * XXX Should-do's:
+ 				 *
+ 				 *	- Limit this only to the actual
+ 				 *	  number of pages mapped by the
+ 				 *	  window.  But the actual window
+ 				 *	  size isn't stored?
+ 				 *
+ 				 *	- Don't deactivate pages on vnodes
+ 				 *	  which are also mmap'd.  But we
+ 				 *	  need to add some sort of counter
+ 				 *	  to uvm_vnode which keeps track
+ 				 *	  of uvn_attach/uvn/detach (i.e.
+ 				 *	  "when things are mmap'd").
+ 				 */
+ 				uvm_lock_pageq();
+ 				for (objoff = umap->offset;
+ 				     objoff < umap->offset + ubc_winsize;
+ 				     objoff += PAGE_SIZE) {
+ 					pg = uvm_pagelookup(oobj, objoff);
+ 					/*
+ 					 * Note we're only looking for pages
+ 					 * on the active queue, so we don't
+ 					 * need to test for wire_count.
+ 					 */
+ 					if (pg == NULL ||
+ 					    (pg->pqflags & PQ_ACTIVE) == 0 ||
+ 					    (pg->flags & PG_BUSY) != 0)
+ 						continue;
+ 					pmap_page_protect(pg, VM_PROT_NONE);
+ 					uvm_pagedeactivate(pg);
+ 					uvmexp.pddeact++;
+ 				}
+ 				uvm_unlock_pageq();
+ 			}
  		}
  
  		umap->uobj = uobj;
***************
*** 408,413 ****
--- 468,478 ----
  		LIST_INSERT_HEAD(&ubc_object.hash[UBC_HASH(uobj, umap_offset)],
  				 umap, hash);
  
+ 		/*
+ 		 * XXX This pmap_remove() should be redundant now
+ 		 * XXX if ubc_recycle_deactivate is TRUE.
+ 		 * XXX --thorpej
+ 		 */
  		va = (vaddr_t)(ubc_object.kva +
  			       (umap - ubc_object.umap) * ubc_winsize);
  		pmap_remove(pmap_kernel(), va, va + ubc_winsize);
***************
*** 462,467 ****
--- 527,577 ----
  	umap->writeoff = 0;
  	umap->writelen = 0;
  	umap->refcount--;
+ 
+ 	/*
+ 	 * Deactivate the pages, if possible.  This saves the
+ 	 * pagedaemon from having to scan them, and also makes
+ 	 * it more likely that these will be thrown away first,
+ 	 * rather than some random process's working set.
+ 	 */
+ 	if (ubc_release_deactivate) {
+ 		vm_page_t pg;
+ 		voff_t objoff;
+ 
+ 		/*
+ 		 * XXX Should-do's:
+ 		 *
+ 		 *	- Limit this only to the actual number
+ 		 *	  of pages mapped by the window.  But
+ 		 *	  "wlen" is not currently meaningful.
+ 		 *
+ 		 *	- Don't deactivate pages on vnodes which
+ 		 *	  are also mmap'd.  But we need to add
+ 		 *	  some sort of counter to uvm_vnode which
+ 		 *	  keeps track of uvn_attach/uvn_detach
+ 		 *	  (i.e. "when things are mmap'd").
+ 		 */
+ 		uvm_lock_pageq();
+ 		for (objoff = umap->offset;
+ 		     objoff < umap->offset + ubc_winsize;
+ 		     objoff += PAGE_SIZE) {
+ 			pg = uvm_pagelookup(uobj, objoff);
+ 			/*
+ 			 * Note, we're only looking for pages on the
+ 			 * active queue, so we don't need to test for
+ 			 * wire_count.
+ 			 */
+ 			if (pg == NULL ||
+ 			    (pg->pqflags & PQ_ACTIVE) == 0 ||
+ 			    (pg->flags & PG_BUSY) != 0)
+ 				continue;
+ 			pmap_page_protect(pg, VM_PROT_NONE);
+ 			uvm_pagedeactivate(pg);
+ 			uvmexp.pddeact++;
+ 		}
+ 		uvm_unlock_pageq();
+ 	}
+ 
  	if (umap->refcount == 0) {
  		if (UBC_RELEASE_UNMAP &&
  		    (((struct vnode *)uobj)->v_flag & VTEXT)) {
***************
*** 478,483 ****
--- 588,598 ----
  			 * as soon as possible.
  			 */
  
+ 			/*
+ 			 * XXX This pmap_remove() should be redundant
+ 			 * XXX now if ubc_release_deactivate is TRUE.
+ 			 * XXX --thorpej
+ 			 */
  			va = (vaddr_t)(ubc_object.kva +
  			    (umap - ubc_object.umap) * ubc_winsize);
  			pmap_remove(pmap_kernel(), va, va + ubc_winsize);