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ipconfig schedule fix

PATCH In review Magnus Damm 2 participants 5 messages Nov 23, 2004 – Nov 24, 2004

Subsystems (3)
Networking Network drivers IPv4/IPv6
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Share & tools
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Magnus Damm

author
#0 lore raw

PATCH 1/1 ipconfig schedule fix

Hi,

This simple patch makes the DHCP/BOOTP/RARP code sleep with schedule_timeout() instead of hogging the cpu with cpu_relax() in a loop. This comes handy when a guest kernel is booted inside QEMU. Without the patch, the host operating system will consume cpu time busy waiting.

Thanks,

/ magnus

net/ipv4/ipconfig.c +6 -9
@@ -1102,8 +1102,8 @@
 
 		jiff = jiffies + (d->next ? CONF_INTER_TIMEOUT : timeout);
 		while (time_before(jiffies, jiff) && !ic_got_reply) {
-			barrier();
-			cpu_relax();
+			set_current_state(TASK_UNINTERRUPTIBLE);
+			schedule_timeout (1);
 		}
 #ifdef IPCONFIG_DHCP
 		/* DHCP isn't done until we get a DHCPACK. */

@@ -1245,7 +1245,6 @@
 
 static int __init ip_auto_config(void)
 {
-	unsigned long jiff;
 	u32 addr;
 
 #ifdef CONFIG_PROC_FS

@@ -1260,18 +1259,16 @@
  try_try_again:
 #endif
 	/* Give hardware a chance to settle */
-	jiff = jiffies + CONF_PRE_OPEN;
-	while (time_before(jiffies, jiff))
-		cpu_relax();
+	set_current_state(TASK_UNINTERRUPTIBLE);
+	schedule_timeout (CONF_PRE_OPEN);
 
 	/* Setup all network devices */
 	if (ic_open_devs() < 0)
 		return -1;
 
 	/* Give drivers a chance to settle */
-	jiff = jiffies + CONF_POST_OPEN;
-	while (time_before(jiffies, jiff))
-		cpu_relax();
+	set_current_state(TASK_UNINTERRUPTIBLE);
+	schedule_timeout (CONF_POST_OPEN);
 
 	/*
 	 * If the config information is insufficient (e.g., our IP address or
maintainer
#1 lore raw
Quoted 5 lines · On Tue, 23 Nov 2004 23:50:35 +0100 Magnus Damm <[email protected]> wrote:

This simple patch makes the DHCP/BOOTP/RARP code sleep with schedule_timeout() instead of hogging the cpu with cpu_relax() in a loop. This comes handy when a guest kernel is booted inside QEMU. Without the patch, the host operating system will consume cpu time busy waiting.

There are two similar loops involving CONF_PRE_OPEN and CONF_POST_OPEN, you may wish to hit those while you're at it.

author
#2 lore raw
Quoted 5 lines · David S. Miller

On Tue, 23 Nov 2004 23:50:35 +0100

Magnus Damm <[email protected]> wrote:

Quoted 8 lines
Quoted 5 lines

This simple patch makes the DHCP/BOOTP/RARP code sleep with schedule_timeout() instead of hogging the cpu with cpu_relax() in a loop. This comes handy when a guest kernel is booted inside QEMU. Without the patch, the host operating system will consume cpu time busy waiting.

There are two similar loops involving CONF_PRE_OPEN and CONF_POST_OPEN, you may wish to hit those while you're at it.

Huh? You mean _removing_ the timeouts involving CONF_PRE/POST_OPEN? I thought my patch converted all busy waits into schedule_timeout()... What am I missing?

/ magnus

maintainer
#3 lore raw
Quoted 12 lines · On Wed, 24 Nov 2004 00:42:17 +0100 Magnus Damm <[email protected]> wrote:
Quoted 11 lines · David S. Miller

On Tue, 23 Nov 2004 23:50:35 +0100

Quoted 5 lines · Magnus Damm

This simple patch makes the DHCP/BOOTP/RARP code sleep with schedule_timeout() instead of hogging the cpu with cpu_relax() in a loop. This comes handy when a guest kernel is booted inside QEMU. Without the patch, the host operating system will consume cpu time busy waiting.

Quoted 6 lines
Quoted 2 lines

There are two similar loops involving CONF_PRE_OPEN and CONF_POST_OPEN, you may wish to hit those while you're at it.

Huh? You mean _removing_ the timeouts involving CONF_PRE/POST_OPEN? I thought my patch converted all busy waits into schedule_timeout()... What am I missing?

No, not removing them, but transforming them likewise into schedule_timeout() calls.

author
#4 lore raw
Quoted 20 lines · David S. Miller

On Wed, 24 Nov 2004 00:42:17 +0100

Quoted 15 lines · Magnus Damm
Quoted 13 lines · David S. Miller

On Tue, 23 Nov 2004 23:50:35 +0100

Quoted 5 lines · Magnus Damm

This simple patch makes the DHCP/BOOTP/RARP code sleep with schedule_timeout() instead of hogging the cpu with cpu_relax() in a loop. This comes handy when a guest kernel is booted inside QEMU. Without the patch, the host operating system will consume cpu time busy waiting.

There are two similar loops involving CONF_PRE_OPEN and CONF_POST_OPEN, you may wish to hit those while you're at it.

Quoted 6 lines
Quoted 3 lines

Huh? You mean _removing_ the timeouts involving CONF_PRE/POST_OPEN? I thought my patch converted all busy waits into schedule_timeout()... What am I missing?

No, not removing them, but transforming them likewise into schedule_timeout() calls.

Yeah, but isn't the patch already doing that? I tried to find more occurances of CONF_PRE/POST_OPEN in the linux-2.6.10-rc2-mm3/net/ipv4/ipconfig.c but I think the patch covers all of them. Please point out what I am missing, maybe it is getting too late for me know...

/ magnus