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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
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