svn commit: r275308 - projects/sendfile/sys/kern

[Gleb Smirnoff]

Author: glebius
Date: Sun Nov 30 09:56:13 2014
New Revision: 275308
URL: https://svnweb.freebsd.org/changeset/base/275308

Log:
  Pager limits our readahead count to MAXPHYS, so do not try to pre-allocate
  larger vector.
  
  Sponsored by:	Netflix
  Sponsored by:	Nginx, Inc.

Modified:
  projects/sendfile/sys/kern/uipc_syscalls.c

Modified: projects/sendfile/sys/kern/uipc_syscalls.c
==============================================================================
--- projects/sendfile/sys/kern/uipc_syscalls.c	Sun Nov 30 09:04:24 2014	(r275307)
+++ projects/sendfile/sys/kern/uipc_syscalls.c	Sun Nov 30 09:56:13 2014	(r275308)
@@ -2467,11 +2467,13 @@ retry_space:
 		/*
 		 * Calculate maximum allowed number of pages for readahead
 		 * at this iteration.  First, we allow readahead up to "rem".
-		 * If application wants more, let it be. But check against
-		 * "obj_size", since vm_pager_has_page() can hint beyond EOF.
+		 * If application wants more, let it be, but there is no
+		 * reason to go above MAXPHYS.  Also check against "obj_size",
+		 * since vm_pager_has_page() can hint beyond EOF.
 		 */
 		rhpages = howmany(rem + (off & PAGE_MASK), PAGE_SIZE) - npages;
 		rhpages = max(SF_READAHEAD(flags), rhpages);
+		rhpages = min(howmany(MAXPHYS, PAGE_SIZE), rhpages);
 		rhpages = min(howmany(obj_size - trunc_page(off), PAGE_SIZE) -
 		    npages, rhpages);