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Date: Thu, 9 Jul 2009 00:34:59 +0200
From: Jarek Poplawski <jarkao2@...il.com>
To: =?UTF-8?B?UGF3ZcWCIFN0YXN6ZXdza2k=?=
<pstaszewski@...are.pl>
Cc: Eric Dumazet <dada1@...mosbay.com>,
Eric Dumazet <eric.dumazet@...il.com>,
Linux Network Development list <netdev@...r.kernel.org>
Subject: Re: weird problem
Pawel Staszewski wrote, On 06/30/2009 10:36 AM:
...
>>>>> rt_worker_func() taking 13% of cpu0 is an alarm for me :)
>>>>> And 21% of cpu0 and 34% of cpu6 taken by oprofiled seems odd too...
Pawel, here is a patch which changes this function (or what it calls)
back to 2.6.28 version; I'm not sure it's OK, so try it very
cautiously...
Cheers,
Jarek P.
--- (for debugging only; apply to 2.6.29.5 or .6)
diff -Nurp a/net/ipv4/route.c b/net/ipv4/route.c
--- a/net/ipv4/route.c 2009-07-08 23:42:15.000000000 +0200
+++ b/net/ipv4/route.c 2009-07-08 22:47:52.000000000 +0200
@@ -769,24 +769,11 @@ static void rt_do_flush(int process_cont
}
}
-/*
- * While freeing expired entries, we compute average chain length
- * and standard deviation, using fixed-point arithmetic.
- * This to have an estimation of rt_chain_length_max
- * rt_chain_length_max = max(elasticity, AVG + 4*SD)
- * We use 3 bits for frational part, and 29 (or 61) for magnitude.
- */
-
-#define FRACT_BITS 3
-#define ONE (1UL << FRACT_BITS)
-
static void rt_check_expire(void)
{
static unsigned int rover;
unsigned int i = rover, goal;
- struct rtable *rth, *aux, **rthp;
- unsigned long samples = 0;
- unsigned long sum = 0, sum2 = 0;
+ struct rtable *rth, **rthp;
u64 mult;
mult = ((u64)ip_rt_gc_interval) << rt_hash_log;
@@ -797,7 +784,6 @@ static void rt_check_expire(void)
goal = rt_hash_mask + 1;
for (; goal > 0; goal--) {
unsigned long tmo = ip_rt_gc_timeout;
- unsigned long length;
i = (i + 1) & rt_hash_mask;
rthp = &rt_hash_table[i].chain;
@@ -805,14 +791,10 @@ static void rt_check_expire(void)
if (need_resched())
cond_resched();
- samples++;
-
if (*rthp == NULL)
continue;
- length = 0;
spin_lock_bh(rt_hash_lock_addr(i));
while ((rth = *rthp) != NULL) {
- prefetch(rth->u.dst.rt_next);
if (rt_is_expired(rth)) {
*rthp = rth->u.dst.rt_next;
rt_free(rth);
@@ -821,46 +803,23 @@ static void rt_check_expire(void)
if (rth->u.dst.expires) {
/* Entry is expired even if it is in use */
if (time_before_eq(jiffies, rth->u.dst.expires)) {
-nofree:
tmo >>= 1;
rthp = &rth->u.dst.rt_next;
- /*
- * We only count entries on
- * a chain with equal hash inputs once
- * so that entries for different QOS
- * levels, and other non-hash input
- * attributes don't unfairly skew
- * the length computation
- */
- for (aux = rt_hash_table[i].chain;;) {
- if (aux == rth) {
- length += ONE;
- break;
- }
- if (compare_hash_inputs(&aux->fl, &rth->fl))
- break;
- aux = aux->u.dst.rt_next;
- }
continue;
}
- } else if (!rt_may_expire(rth, tmo, ip_rt_gc_timeout))
- goto nofree;
+ } else if (!rt_may_expire(rth, tmo, ip_rt_gc_timeout)) {
+ tmo >>= 1;
+ rthp = &rth->u.dst.rt_next;
+ continue;
+ }
/* Cleanup aged off entries. */
*rthp = rth->u.dst.rt_next;
rt_free(rth);
}
spin_unlock_bh(rt_hash_lock_addr(i));
- sum += length;
- sum2 += length*length;
- }
- if (samples) {
- unsigned long avg = sum / samples;
- unsigned long sd = int_sqrt(sum2 / samples - avg*avg);
- rt_chain_length_max = max_t(unsigned long,
- ip_rt_gc_elasticity,
- (avg + 4*sd) >> FRACT_BITS);
}
+ rt_chain_length_max = ip_rt_gc_elasticity;
rover = i;
}
--
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