[Devel] [RFC PATCH vz9 5/5] ploop: convert wait_list and wb_batch_llist to use lockless lists

[Alexander Atanasov]

On 9.10.24 19:09, Denis V. Lunev wrote:
> On 10/7/24 13:12, Alexander Atanasov wrote:
>> Convert to lockless lists - intermix with regular list due to
>> that next pointer in both list_head and llist_head is the first
>> field, and prev is not used. Do this so we can make babysteps
>> forward.
[cut]
> I observe
> [w(1)][52.5%][w=644MiB/s][w=165k IOPS][eta 00m:28s] <- 1 thread, partition
> 1 (f=1): [w(1)][15.0%][w=715MiB/s][w=183k IOPS][eta 00m:51s] <- thread 
> device
> [w(12)][25.0%][w=1376MiB/s][w=352k IOPS][eta 00m:45s] <- 12 threads
> 
> 
> Do we expect to have a difference right now?


These are minor and preparations - converted lists are about metadata 
writeback only.
I expect improvement when the use of deferred lock is eliminated/reduced 
to minimum which will happen when the rest of the lists are converted, 
i.e. when all pios are moved lockless and contention is reduced.


-- 
Regards,
Alexander Atanasov