[Ocfs2-devel] [PATCH] ocfs2: Optimize the reading of heartbeat data

[Jia Guo]

Hi Joseph:

On 2018/10/24 11:02, Joseph Qi wrote:
> Hi,
> 
> On 18/10/23 20:32, Jia Guo wrote:
>> Reading heartbeat data from lowest node rather than from zero, in
>> cases where the node is not defined from zero, can reduce the number
>> of sectors read.
>>
>> Here is a simple test data obtained with 'iostat -dmx dm-5 2', with
>> two nodes in the cluster, node number 10, 20, respectively.
>> Before optimization:
>> Device:         rrqm/s   wrqm/s     r/s     w/s    rMB/s    wMB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
>> dm-5              0.00     0.00    0.50    0.50     0.01     0.00    11.00     0.00    1.00    1.00    1.00   1.50   0.15
>> After the optimization:
>> Device:         rrqm/s   wrqm/s     r/s     w/s    rMB/s    wMB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
>> dm-5              0.00     0.00    0.50    0.50     0.00     0.00     6.00     0.00    0.50    1.00    0.00   0.50   0.05
>>
>> Signed-off-by: Jia Guo <guojia12 at huawei.com>
>> Reviewed-by: Jun Piao <piaojun at huawei.com>
>> Reviewed-by: Yiwen Jiang <jiangyiwen at huawei.com>
>> ---
>>  cluster/heartbeat.c | 23 +++++++++++++++--------
>>  1 file changed, 15 insertions(+), 8 deletions(-)
>>
>> diff --git a/cluster/heartbeat.c b/cluster/heartbeat.c
>> index 9b2ed62..a9cf984 100644
>> --- a/cluster/heartbeat.c
>> +++ b/cluster/heartbeat.c
>> @@ -582,17 +582,18 @@ bail:
>>  }
>>
>>  static int o2hb_read_slots(struct o2hb_region *reg,
>> -			   unsigned int max_slots)
>> +			   unsigned int min_slot,
>> +			   unsigned int max_slot)
> 
> I don't think changing max_slots to max_slot here is appropriate.
> max_slots stands for number of slots totally, while max_slot stands
> for the maximum slot number, corresponding with the minimum slot
> number. 
> The passing value of the caller hints this.
> 
> Thanks,
> Joseph
> 

I will fix this in PATCH v2.

Thanks,
Jia

>>  {
>> -	unsigned int current_slot=0;
>> +	unsigned int current_slot = min_slot;
>>  	int status;
>>  	struct o2hb_bio_wait_ctxt wc;
>>  	struct bio *bio;
>>
>>  	o2hb_bio_wait_init(&wc);
>>
>> -	while(current_slot < max_slots) {
>> -		bio = o2hb_setup_one_bio(reg, &wc, &current_slot, max_slots,
>> +	while(current_slot < max_slot) {
>> +		bio = o2hb_setup_one_bio(reg, &wc, &current_slot, max_slot,
>>  					 REQ_OP_READ, 0);
>>  		if (IS_ERR(bio)) {
>>  			status = PTR_ERR(bio);
>> @@ -1093,9 +1094,14 @@ static int o2hb_highest_node(unsigned long *nodes, int numbits)
>>  	return find_last_bit(nodes, numbits);
>>  }
>>
>> +static int o2hb_lowest_node(unsigned long *nodes, int numbits)
>> +{
>> +	return find_first_bit(nodes, numbits);
>> +}
>> +
>>  static int o2hb_do_disk_heartbeat(struct o2hb_region *reg)
>>  {
>> -	int i, ret, highest_node;
>> +	int i, ret, highest_node, lowest_node;
>>  	int membership_change = 0, own_slot_ok = 0;
>>  	unsigned long configured_nodes[BITS_TO_LONGS(O2NM_MAX_NODES)];
>>  	unsigned long live_node_bitmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
>> @@ -1120,7 +1126,8 @@ static int o2hb_do_disk_heartbeat(struct o2hb_region *reg)
>>  	}
>>
>>  	highest_node = o2hb_highest_node(configured_nodes, O2NM_MAX_NODES);
>> -	if (highest_node >= O2NM_MAX_NODES) {
>> +	lowest_node = o2hb_lowest_node(configured_nodes, O2NM_MAX_NODES);
>> +	if (highest_node >= O2NM_MAX_NODES || lowest_node >= O2NM_MAX_NODES) {
>>  		mlog(ML_NOTICE, "o2hb: No configured nodes found!\n");
>>  		ret = -EINVAL;
>>  		goto bail;
>> @@ -1130,7 +1137,7 @@ static int o2hb_do_disk_heartbeat(struct o2hb_region *reg)
>>  	 * yet. Of course, if the node definitions have holes in them
>>  	 * then we're reading an empty slot anyway... Consider this
>>  	 * best-effort. */
>> -	ret = o2hb_read_slots(reg, highest_node + 1);
>> +	ret = o2hb_read_slots(reg, lowest_node, highest_node + 1);
>>  	if (ret < 0) {
>>  		mlog_errno(ret);
>>  		goto bail;
>> @@ -1801,7 +1808,7 @@ static int o2hb_populate_slot_data(struct o2hb_region *reg)
>>  	struct o2hb_disk_slot *slot;
>>  	struct o2hb_disk_heartbeat_block *hb_block;
>>
>> -	ret = o2hb_read_slots(reg, reg->hr_blocks);
>> +	ret = o2hb_read_slots(reg, 0, reg->hr_blocks);
>>  	if (ret)
>>  		goto out;
>>
> .
>