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Re: [Xen-devel] [PATCH] switch rangeset's lock to rwlock



>>> On 19.09.14 at 18:32, <konrad.wilk@xxxxxxxxxx> wrote:
> On Fri, Sep 12, 2014 at 01:55:07PM +0100, Jan Beulich wrote:
>> As a general library routine, it should behave as efficiently as
>> possible, even if at present no significant contention is known here.
>> 
> 
> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> 
> I am comfortable with this going to Xen 4.5.

Anyone of you wanting to ack this then, or should I nevertheless
postpone it until after 4.5?

Jan

>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>> ---
>> With the widened use of rangesets I'd like to re-suggest this change
>> which I had posted already a couple of years back.
>> 
>> --- a/xen/common/rangeset.c
>> +++ b/xen/common/rangeset.c
>> @@ -28,7 +28,7 @@ struct rangeset {
>>  
>>      /* Number of ranges that can be allocated */
>>      long             nr_ranges;
>> -    spinlock_t       lock;
>> +    rwlock_t         lock;
>>  
>>      /* Pretty-printing name. */
>>      char             name[32];
>> @@ -120,7 +120,7 @@ int rangeset_add_range(
>>  
>>      ASSERT(s <= e);
>>  
>> -    spin_lock(&r->lock);
>> +    write_lock(&r->lock);
>>  
>>      x = find_range(r, s);
>>      y = find_range(r, e);
>> @@ -176,7 +176,7 @@ int rangeset_add_range(
>>      }
>>  
>>   out:
>> -    spin_unlock(&r->lock);
>> +    write_unlock(&r->lock);
>>      return rc;
>>  }
>>  
>> @@ -188,7 +188,7 @@ int rangeset_remove_range(
>>  
>>      ASSERT(s <= e);
>>  
>> -    spin_lock(&r->lock);
>> +    write_lock(&r->lock);
>>  
>>      x = find_range(r, s);
>>      y = find_range(r, e);
>> @@ -244,7 +244,7 @@ int rangeset_remove_range(
>>      }
>>  
>>   out:
>> -    spin_unlock(&r->lock);
>> +    write_unlock(&r->lock);
>>      return rc;
>>  }
>>  
>> @@ -256,10 +256,10 @@ int rangeset_contains_range(
>>  
>>      ASSERT(s <= e);
>>  
>> -    spin_lock(&r->lock);
>> +    read_lock(&r->lock);
>>      x = find_range(r, s);
>>      contains = (x && (x->e >= e));
>> -    spin_unlock(&r->lock);
>> +    read_unlock(&r->lock);
>>  
>>      return contains;
>>  }
>> @@ -272,10 +272,10 @@ int rangeset_overlaps_range(
>>  
>>      ASSERT(s <= e);
>>  
>> -    spin_lock(&r->lock);
>> +    read_lock(&r->lock);
>>      x = find_range(r, e);
>>      overlaps = (x && (s <= x->e));
>> -    spin_unlock(&r->lock);
>> +    read_unlock(&r->lock);
>>  
>>      return overlaps;
>>  }
>> @@ -287,13 +287,13 @@ int rangeset_report_ranges(
>>      struct range *x;
>>      int rc = 0;
>>  
>> -    spin_lock(&r->lock);
>> +    read_lock(&r->lock);
>>  
>>      for ( x = find_range(r, s); x && (x->s <= e) && !rc; x = next_range(r, 
>> x) )
>>          if ( x->e >= s )
>>              rc = cb(max(x->s, s), min(x->e, e), ctxt);
>>  
>> -    spin_unlock(&r->lock);
>> +    read_unlock(&r->lock);
>>  
>>      return rc;
>>  }
>> @@ -331,7 +331,7 @@ struct rangeset *rangeset_new(
>>      if ( r == NULL )
>>          return NULL;
>>  
>> -    spin_lock_init(&r->lock);
>> +    rwlock_init(&r->lock);
>>      INIT_LIST_HEAD(&r->range_list);
>>      r->nr_ranges = -1;
>>  
>> @@ -414,21 +414,21 @@ void rangeset_swap(struct rangeset *a, s
>>  
>>      if ( a < b )
>>      {
>> -        spin_lock(&a->lock);
>> -        spin_lock(&b->lock);
>> +        write_lock(&a->lock);
>> +        write_lock(&b->lock);
>>      }
>>      else
>>      {
>> -        spin_lock(&b->lock);
>> -        spin_lock(&a->lock);
>> +        write_lock(&b->lock);
>> +        write_lock(&a->lock);
>>      }
>>  
>>      list_splice_init(&a->range_list, &tmp);
>>      list_splice_init(&b->range_list, &a->range_list);
>>      list_splice(&tmp, &b->range_list);
>>  
>> -    spin_unlock(&a->lock);
>> -    spin_unlock(&b->lock);
>> +    write_unlock(&a->lock);
>> +    write_unlock(&b->lock);
>>  }
>>  
>>  /*****************************
>> @@ -446,7 +446,7 @@ void rangeset_printk(
>>      int nr_printed = 0;
>>      struct range *x;
>>  
>> -    spin_lock(&r->lock);
>> +    read_lock(&r->lock);
>>  
>>      printk("%-10s {", r->name);
>>  
>> @@ -465,7 +465,7 @@ void rangeset_printk(
>>  
>>      printk(" }");
>>  
>> -    spin_unlock(&r->lock);
>> +    read_unlock(&r->lock);
>>  }
>>  
>>  void rangeset_domain_printk(
>> 
>> 
>> 
> 
>> switch rangeset's lock to rwlock
>> 
>> As a general library routine, it should behave as efficiently as
>> possible, even if at present no significant contention is known here.
>> 
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>> ---
>> With the widened use of rangesets I'd like to re-suggest this change
>> which I had posted already a couple of years back.
>> 
>> --- a/xen/common/rangeset.c
>> +++ b/xen/common/rangeset.c
>> @@ -28,7 +28,7 @@ struct rangeset {
>>  
>>      /* Number of ranges that can be allocated */
>>      long             nr_ranges;
>> -    spinlock_t       lock;
>> +    rwlock_t         lock;
>>  
>>      /* Pretty-printing name. */
>>      char             name[32];
>> @@ -120,7 +120,7 @@ int rangeset_add_range(
>>  
>>      ASSERT(s <= e);
>>  
>> -    spin_lock(&r->lock);
>> +    write_lock(&r->lock);
>>  
>>      x = find_range(r, s);
>>      y = find_range(r, e);
>> @@ -176,7 +176,7 @@ int rangeset_add_range(
>>      }
>>  
>>   out:
>> -    spin_unlock(&r->lock);
>> +    write_unlock(&r->lock);
>>      return rc;
>>  }
>>  
>> @@ -188,7 +188,7 @@ int rangeset_remove_range(
>>  
>>      ASSERT(s <= e);
>>  
>> -    spin_lock(&r->lock);
>> +    write_lock(&r->lock);
>>  
>>      x = find_range(r, s);
>>      y = find_range(r, e);
>> @@ -244,7 +244,7 @@ int rangeset_remove_range(
>>      }
>>  
>>   out:
>> -    spin_unlock(&r->lock);
>> +    write_unlock(&r->lock);
>>      return rc;
>>  }
>>  
>> @@ -256,10 +256,10 @@ int rangeset_contains_range(
>>  
>>      ASSERT(s <= e);
>>  
>> -    spin_lock(&r->lock);
>> +    read_lock(&r->lock);
>>      x = find_range(r, s);
>>      contains = (x && (x->e >= e));
>> -    spin_unlock(&r->lock);
>> +    read_unlock(&r->lock);
>>  
>>      return contains;
>>  }
>> @@ -272,10 +272,10 @@ int rangeset_overlaps_range(
>>  
>>      ASSERT(s <= e);
>>  
>> -    spin_lock(&r->lock);
>> +    read_lock(&r->lock);
>>      x = find_range(r, e);
>>      overlaps = (x && (s <= x->e));
>> -    spin_unlock(&r->lock);
>> +    read_unlock(&r->lock);
>>  
>>      return overlaps;
>>  }
>> @@ -287,13 +287,13 @@ int rangeset_report_ranges(
>>      struct range *x;
>>      int rc = 0;
>>  
>> -    spin_lock(&r->lock);
>> +    read_lock(&r->lock);
>>  
>>      for ( x = find_range(r, s); x && (x->s <= e) && !rc; x = next_range(r, 
>> x) )
>>          if ( x->e >= s )
>>              rc = cb(max(x->s, s), min(x->e, e), ctxt);
>>  
>> -    spin_unlock(&r->lock);
>> +    read_unlock(&r->lock);
>>  
>>      return rc;
>>  }
>> @@ -331,7 +331,7 @@ struct rangeset *rangeset_new(
>>      if ( r == NULL )
>>          return NULL;
>>  
>> -    spin_lock_init(&r->lock);
>> +    rwlock_init(&r->lock);
>>      INIT_LIST_HEAD(&r->range_list);
>>      r->nr_ranges = -1;
>>  
>> @@ -414,21 +414,21 @@ void rangeset_swap(struct rangeset *a, s
>>  
>>      if ( a < b )
>>      {
>> -        spin_lock(&a->lock);
>> -        spin_lock(&b->lock);
>> +        write_lock(&a->lock);
>> +        write_lock(&b->lock);
>>      }
>>      else
>>      {
>> -        spin_lock(&b->lock);
>> -        spin_lock(&a->lock);
>> +        write_lock(&b->lock);
>> +        write_lock(&a->lock);
>>      }
>>  
>>      list_splice_init(&a->range_list, &tmp);
>>      list_splice_init(&b->range_list, &a->range_list);
>>      list_splice(&tmp, &b->range_list);
>>  
>> -    spin_unlock(&a->lock);
>> -    spin_unlock(&b->lock);
>> +    write_unlock(&a->lock);
>> +    write_unlock(&b->lock);
>>  }
>>  
>>  /*****************************
>> @@ -446,7 +446,7 @@ void rangeset_printk(
>>      int nr_printed = 0;
>>      struct range *x;
>>  
>> -    spin_lock(&r->lock);
>> +    read_lock(&r->lock);
>>  
>>      printk("%-10s {", r->name);
>>  
>> @@ -465,7 +465,7 @@ void rangeset_printk(
>>  
>>      printk(" }");
>>  
>> -    spin_unlock(&r->lock);
>> +    read_unlock(&r->lock);
>>  }
>>  
>>  void rangeset_domain_printk(
> 
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@xxxxxxxxxxxxx 
>> http://lists.xen.org/xen-devel 



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