gentoo-overlay/sys-apps/preload/files/0001-Early-restart-of-forking-readahead-children.patch

From 63cbd8862714a97c8ef752041dc8c351ba4fae1d Mon Sep 17 00:00:00 2001
From: Kai Krakow <kai@kaishome.de>
Date: Mon, 28 Jul 2008 19:50:22 +0200
Subject: [PATCH] Early restart of forking readahead children

This patch adds ability to wait_for_children() to restart
forking new readahead children as soon as a slot becomes
available which should make the effect of parallelism even
more effective. Previous situation was:

Wait for all children to exit as soon as the high water mark
was reached. This resulted in 30 processes in peak, wait for
them to reach 0 processes. Start another 30 processes in
peak, wait again etc.

New situation is: Start a new process as soon as a previous
process exited which keeps the peak at 30 processes until
the readahead list is finished.

This introduces a new parameter to wait_for_children() which
tells it to leave now more than XY processes running when
returning.
---
 src/readahead.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/readahead.c b/src/readahead.c
index c169e81..7617449 100644
--- a/src/readahead.c
+++ b/src/readahead.c
@@ -103,10 +103,10 @@ map_block_compare (const preload_map_t **pa, const preload_map_t **pb)
 static int procs = 0;
 
 static void
-wait_for_children (void)
+wait_for_children (int maxprocs)
 {
   /* wait for child processes to terminate */
-  while (procs > 0)
+  while (procs >= maxprocs)
     {
       int status;
       if (wait (&status) > 0)
@@ -121,7 +121,7 @@ process_file(const char *path, size_t offset, size_t length)
   int maxprocs = conf->system.maxprocs;
 
   if (procs >= maxprocs)
-    wait_for_children ();
+    wait_for_children (maxprocs);
 
   if (maxprocs > 0)
     {
@@ -257,7 +257,7 @@ preload_readahead (preload_map_t **files, int file_count)
       path = NULL;
     }
 
-  wait_for_children ();
+  wait_for_children (0);
 
   return processed;
 }
-- 
1.5.4.5