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[IA64] Remove needless delay in MCA rendezvous 

While testing the MCA recovery code, noticed that some machines would have a
five second delay rendezvousing cpus.  What was happening is that
ia64_wait_for_slaves() would check to see if all the slave CPUs had
rendezvoused.  If any had not, it would wait 1 millisecond then check again.
If any CPUs had still not rendezvoused, it would wait 5 seconds before
checking again.

On some configs the rendezvous takes more than 1 millisecond, causing the code
to wait the full 5 seconds, even though the last CPU rendezvoused after only
a few milliseconds.

The fix is to check every 1 millisecond to see if all the cpus have
rendezvoused.  After 5 seconds the code concludes the CPUs will never
rendezvous (same as before).

The MCA code is, by definition, not performance critical, but a needless
delay of 5 seconds is senseless.  The 5 seconds also adds up quickly
when running the error injection code in a loop.

This patch both simplifies the code and removes the needless delay.

Signed-off-by: Russ Anderson <rja@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
Russ Anderson 2007-09-20 13:59:12 -05:00 committed by Tony Luck
parent 28eda5b8b4
commit 2bc5c28299
1 changed files with 19 additions and 22 deletions
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41
arch/ia64/kernel/mca.c
View File

@ -1135,30 +1135,27 @@ no_mod:
static void
ia64_wait_for_slaves(int monarch, const char *type)
{
int c, wait = 0, missing = 0;
for_each_online_cpu(c) {
if (c == monarch)
continue;
if (ia64_mc_info.imi_rendez_checkin[c] == IA64_MCA_RENDEZ_CHECKIN_NOTDONE) {
udelay(1000); /* short wait first */
wait = 1;
break;
int c, i , wait;
/*
* wait 5 seconds total for slaves (arbitrary)
*/
for (i = 0; i < 5000; i++) {
wait = 0;
for_each_online_cpu(c) {
if (c == monarch)
continue;
if (ia64_mc_info.imi_rendez_checkin[c]
== IA64_MCA_RENDEZ_CHECKIN_NOTDONE) {
udelay(1000); /* short wait */
wait = 1;
break;
}
}
if (!wait)
goto all_in;
}
if (!wait)
goto all_in;
for_each_online_cpu(c) {
if (c == monarch)
continue;
if (ia64_mc_info.imi_rendez_checkin[c] == IA64_MCA_RENDEZ_CHECKIN_NOTDONE) {
udelay(5*1000000); /* wait 5 seconds for slaves (arbitrary) */
if (ia64_mc_info.imi_rendez_checkin[c] == IA64_MCA_RENDEZ_CHECKIN_NOTDONE)
missing = 1;
break;
}
}
if (!missing)
goto all_in;
/*
* Maybe slave(s) dead. Print buffered messages immediately.
*/