Patchwork weird problem

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Submitter Jarek Poplawski
Date July 8, 2009, 10:34 p.m.
Message ID <20090708223459.GB3666@ami.dom.local>
Download mbox | patch
Permalink /patch/29614/
State RFC
Delegated to: David Miller
Headers show

Comments

Jarek Poplawski - July 8, 2009, 10:34 p.m.
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)

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Paweł Staszewski - July 9, 2009, 11:14 p.m.
Jarek Poplawski pisze:
> 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)
>
>   
I added this patch 30min ago - all is working but problem still exist.

There is only one change - without this patch cpu load was rising from 
40 to 50%
With this patch there is 15 to 25% cpu load.


> 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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Paweł Staszewski - July 9, 2009, 11:59 p.m.
Today i make other tests with change of 
/proc/sys/net/ipv4/rt_cache_rebuild_count and kernel 2.6.30.1

And when rt_cache_rebuild_count is set to "-1" i have always load on 
x86_64 machine approx 40-50% of each cpu where network card is binded by 
irq_aff

when rt_cache_rebuild_count is set to more than "-1" i have 15 to 20 sec 
of 1 to 3% cpu and after 40-50% cpu

I attach some oprofile output for
rt_cache_rebuild_count = 4 - oprofile_rt_cache_rebuild_count_4.txt
and
rt_cache_rebuild_count = -1 - oprofile_rt_cache_rebuild_count_-1.txt


Regards
Pawel Staszewski

Paweł Staszewski pisze:
> Jarek Poplawski pisze:
>> 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)
>>
>>   
> I added this patch 30min ago - all is working but problem still exist.
>
> There is only one change - without this patch cpu load was rising from 
> 40 to 50%
> With this patch there is 15 to 25% cpu load.
>
>
>> 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;
>>  }
>>  
>>
>>
>>   
>
> -- 
> To unsubscribe from this list: send the line "unsubscribe netdev" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>
CPU: Core 2, speed 2999.65 MHz (estimated)
Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a unit mask of 0x00 (Unhalted core cycles) count 100000
Samples on CPU 0
Samples on CPU 1
Samples on CPU 2
Samples on CPU 3
Samples on CPU 4
Samples on CPU 5
Samples on CPU 6
Samples on CPU 7
samples  %        samples  %        samples  %        samples  %        samples  %        samples  %        samples  %        samples  %        image name
           app name                 symbol name
2051     17.8488  0              0  0              0  0              0  0              0  0              0  0              0  0              0  oprofiled
           oprofiled                (no symbols)
1845     16.0560  16362     4.7340  22049     4.2067  1949     16.5197  100       9.6618  43       10.2625  95       10.5205  49        2.3512  vmlinux
           vmlinux                  mwait_idle
1126      9.7990  0              0  0              0  0              0  0              0  0              0  0              0  0              0  vmlinux
           vmlinux                  rt_worker_func
751       6.5355  51        0.0148  53        0.0101  5         0.0424  3         0.2899  0              0  4         0.4430  16        0.7678  vmlinux
           vmlinux                  free_block
621       5.4042  0              0  4        7.6e-04  3766     31.9207  1         0.0966  0              0  0              0  686      32.9175  opreport
           opreport                 (no symbols)
568       4.9430  25        0.0072  38        0.0073  0              0  0              0  0              0  0              0  0              0  vmlinux
           vmlinux                  dst_destroy
303       2.6368  2        5.8e-04  6         0.0011  106       0.8985  0              0  0              0  5         0.5537  26        1.2476  vmlinux
           vmlinux                  copy_user_generic_string
296       2.5759  17175     4.9692  23050     4.3977  196       1.6613  59        5.7005  28        6.6826  71        7.8627  63        3.0230  vmlinux
           vmlinux                  _raw_spin_lock
267       2.3236  21        0.0061  3044      0.5808  1328     11.2561  3         0.2899  1         0.2387  26        2.8793  265      12.7159  libc-2.8.so
           libc-2.8.so              (no symbols)
261       2.2713  0              0  1        1.9e-04  36        0.3051  0              0  0              0  1         0.1107  6         0.2879  vmlinux
           vmlinux                  search_by_key
247       2.1495  9         0.0026  21        0.0040  3         0.0254  1         0.0966  0              0  0              0  0              0  vmlinux
           vmlinux                  __call_rcu
219       1.9058  0              0  0              0  1177      9.9763  0              0  0              0  0              0  247      11.8522  libstdc++.so.6
.0.10      libstdc++.so.6.0.10      (no symbols)
150       1.3054  1606      0.4647  2104      0.4014  5         0.0424  2         0.1932  3         0.7160  2         0.2215  1         0.0480  vmlinux
           vmlinux                  get_next_timer_interrupt
138       1.2009  15        0.0043  23        0.0044  2         0.0170  2         0.1932  0              0  3         0.3322  1         0.0480  vmlinux
           vmlinux                  __rcu_process_callbacks
105       0.9138  321       0.0929  368       0.0702  44        0.3729  271      26.1836  54       12.8878  63        6.9767  57        2.7351  vmlinux
           vmlinux                  tg_shares_up
100       0.8702  27        0.0078  16        0.0031  0              0  0              0  0              0  0              0  0              0  vmlinux
           vmlinux                  memmove
88        0.7658  1        2.9e-04  7         0.0013  488       4.1363  0              0  0              0  16        1.7719  121       5.8061  vmlinux
           vmlinux                  clear_page_c
86        0.7484  0              0  0              0  454       3.8481  0              0  0              0  0              0  96        4.6065  libbfd-2.18.so
           libbfd-2.18.so           (no symbols)
65        0.5657  0              0  2        3.8e-04  2         0.0170  0              0  0              0  0              0  0              0  vmlinux
           vmlinux                  __find_get_block
62        0.5396  1536      0.4444  3313      0.6321  15        0.1271  4         0.3865  0              0  4         0.4430  5         0.2399  vmlinux
           vmlinux                  _raw_spin_unlock
57        0.4960  0              0  0              0  0              0  0              0  0              0  0              0  0              0  vmlinux
           vmlinux                  create_virtual_node
52        0.4525  6         0.0017  0              0  930       7.8827  50        4.8309  163      38.9021  95       10.5205  13        0.6238  vmlinux
           vmlinux                  mutex_spin_on_owner
50        0.4351  2        5.8e-04  2        3.8e-04  0              0  0              0  0              0  0              0  0              0  vmlinux
           vmlinux                  dst_rcu_free
49        0.4264  477       0.1380  871       0.1662  2         0.0170  1         0.0966  0              0  0              0  1         0.0480  vmlinux
CPU: Core 2, speed 2999.65 MHz (estimated)
Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a unit mask of 0x00 (Unhalted core cycles) count 100000
Samples on CPU 0
Samples on CPU 1
Samples on CPU 2
Samples on CPU 3
Samples on CPU 4
Samples on CPU 5
Samples on CPU 6
Samples on CPU 7
samples  %        samples  %        samples  %        samples  %        samples  %        samples  %        samples  %        samples  %        image name
           app name                 symbol name
5233     15.7190  760       0.0795  259       0.0190  10        0.1857  0              0  1         0.1247  340       9.6454  20        1.4006  libc-2.8.so
           libc-2.8.so              (no symbols)
5116     15.3675  0              0  0              0  0              0  0              0  0              0  0              0  0              0  bgpd
           bgpd                     bgp_best_selection
4499     13.5142  37423     3.9162  47399     3.4832  4615     85.7010  918       9.9804  172      21.4464  540      15.3191  191      13.3754  vmlinux
           vmlinux                  mwait_idle
3635     10.9189  0              0  2102      0.1545  0              0  0              0  0              0  0              0  0              0  oprofiled
           oprofiled                (no symbols)
2855      8.5759  765       0.0801  0              0  0              0  0              0  0              0  0              0  0              0  bgpd
           bgpd                     bgp_route_next
1626      4.8842  372       0.0389  0              0  0              0  0              0  0              0  0              0  0              0  bgpd
           bgpd                     bgp_scan_timer
1611      4.8391  0              0  0              0  0              0  0              0  0              0  0              0  0              0  bgpd
           bgpd                     bgp_process_main
1133      3.4033  1        1.0e-04  0              0  0              0  0              0  0              0  0              0  0              0  bgpd
           bgpd                     bgp_process_announce_selected
950       2.8536  218       0.0228  0              0  0              0  0              0  0              0  0              0  0              0  bgpd
           bgpd                     bgp_process
486       1.4599  11        0.0012  240       0.0176  1         0.0186  0              0  0              0  31        0.8794  1         0.0700  vmlinux
           vmlinux                  copy_user_generic_string
442       1.3277  111       0.0116  0              0  0              0  0              0  0              0  0              0  0              0  bgpd
           bgpd                     bgp_nexthop_lookup
376       1.1294  1        1.0e-04  0              0  0              0  0              0  0              0  0              0  0              0  libzebra.so.0.
0.0        libzebra.so.0.0.0        work_queue_run
323       0.9702  82        0.0086  2        1.5e-04  0              0  0              0  0              0  0              0  0              0  libzebra.so.0.
0.0        libzebra.so.0.0.0        prefix_match
237       0.7119  64        0.0067  1        7.3e-05  0              0  0              0  0              0  0              0  0              0  libzebra.so.0.
0.0        libzebra.so.0.0.0        zcalloc
216       0.6488  0              0  0              0  0              0  0              0  0              0  0              0  0              0  vmlinux
           vmlinux                  rt_worker_func
203       0.6098  3070      0.3213  4038      0.2967  7         0.1300  32        0.3479  13        1.6209  3         0.0851  6         0.4202  vmlinux
           vmlinux                  get_next_timer_interrupt
192       0.5767  30        0.0031  0              0  0              0  0              0  0              0  0              0  0              0  libzebra.so.0.
0.0        libzebra.so.0.0.0        .plt
189       0.5677  0              0  0              0  0              0  0              0  0              0  0              0  0              0  bgpd
           bgpd                     bgp_adj_out_unset
187       0.5617  40562     4.2447  54422     3.9993  65        1.2071  409       4.4466  73        9.1022  126       3.5745  116       8.1232  vmlinux
           vmlinux                  _raw_spin_lock
144       0.4325  60        0.0063  3        2.2e-04  0              0  0              0  0              0  0              0  0              0  bgpd
           bgpd                     bgp_node_get
127       0.3815  40        0.0042  0              0  0              0  0              0  0              0  0              0  0              0  libzebra.so.0.
0.0        libzebra.so.0.0.0        listnode_add
124       0.3725  1183      0.1238  1623      0.1193  72        1.3370  2894     31.4634  90       11.2219  108       3.0638  191      13.3754  vmlinux
           vmlinux                  tg_shares_up
119       0.3575  0              0  13       9.6e-04  0              0  0              0  0              0  0              0  0              0  vmlinux
           vmlinux                  mutex_spin_on_owner
114       0.3424  14        0.0015  0              0  0              0  0              0  0              0  0              0  0              0  bgpd

Patch

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;
 }