Re: [PATCH] scsi: megaraid_sas: disabled shared host tagset feature by default

[mengfanhui <mengfanhui@kylinos.cn>]

We are analyzing the kylinos issue and found that the performance degradation caused by patch 103fbf8e4020845e4fcf63819288cedb092a3c91.
It will change the working mode of the disk, It will lead to performance degradation.Currently driver has provision to disable host-wide 
tags using "host_tagset_enable" module parameter.


在 2024/3/11 17:30, John Garry 写道:
> On 11/03/2024 08:54, mengfanhui wrote:
>> By default, the host_tagset_enable feature is disabled，Fio performance
>> has improved significantly
>>
>> fio test command:
>> sudo fio -filename=/fio_test -direct=1 -iodepth 32 -thread -rw=write -ioengine=libaio
>> -bs=4K -size=5120M -runtime=600 -numjobs=$CPUN -group_reporting -name=**.result >> **.result
>>
>> The test data results bw  are as follows：
>>                v6.8_kernel       v6.8_kernel_disable_host_tagset
>> 4k randwrite     375                     642
>> 4k randread      210                     784
>> 4k  write        306                     387
>> 4k  read         435                     2457
>> 128k write       355                     380
>> 128k read        976                     3665
>> 1M   read        415                     3122
>>
> 
> There are some huge differences in those numbers. Can you find out what is going on?
> 
>> Signed-off-by: mengfanhui <mengfanhui@kylinos.cn>
>> ---
>>   drivers/scsi/megaraid/megaraid_sas_base.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
>> index 3d4f13da1ae8..da19c4c07f2f 100644
>> --- a/drivers/scsi/megaraid/megaraid_sas_base.c
>> +++ b/drivers/scsi/megaraid/megaraid_sas_base.c
>> @@ -123,9 +123,9 @@ MODULE_PARM_DESC(poll_queues, "Number of queues to be use for io_uring poll mode
>>           "High iops queues are not allocated &\n\t\t"
>>           );
>>   -int host_tagset_enable = 1;
>> +int host_tagset_enable;
>>   module_param(host_tagset_enable, int, 0444);
>> -MODULE_PARM_DESC(host_tagset_enable, "Shared host tagset enable/disable Default: enable(1)");
>> +MODULE_PARM_DESC(host_tagset_enable, "Shared host tagset enable/disable Default: disable(0)");
>>     MODULE_LICENSE("GPL");
>>   MODULE_VERSION(MEGASAS_VERSION);
>