Re: [PATCH] qla2xxx: Resolved a performance issue in interrupt handler

Anirban Chakraborty
2009-06-10T16:09:13Z

On Jun 10, 2009, at 8:52 AM, Styner, Douglas W wrote:

>
> Anirban Chakraborty [mailto:anirban.chakraborty@qlogic.com] write:
>>
>> You got it right. Basically we are doing:
>> 1. baseline scsi-misc + earlier patch
>> 2. baseline scsi-misc + this patch
>> And then compare 1 and 2.
>
> Results are as follows:
> Total interrupts are down slightly (-0.8%), QLA interrupts are flat
> (-0.1%) Cycles for qla2xxx_intr_handler up from .77% to .92%.

So, it looks like using spin_lock_irqsave is doing a better job than
globally disabling the sharing of the interrupt via IRQF_DISABLED.
-Anirban

>
>
> Linux OLTP Performance summary
> Kernel# Speedup(x) Intr/s CtxSw/s us% sy% id
> % wa%
> 2.6.30-rc6_scsi-misc_0001 1.000 29538 43374 75 25
> 0 0
> 2.6.30-rc6_scsi-misc_irqf-d 1.000 29286 43125 74 25
> 0 1
>
> Server configurations:
> Intel Xeon Quad-core 2.0GHz 2 cpus/8 cores/8 threads
> 64GB memory, 3 qle2462 FC HBA, 450 spindles (30 logical units)
>
>
> ======oprofile CPU_CLK_UNHALTED for top 30 functions
> Cycles% 2.6.30-rc6_scsi-misc_0001 Cycles% 2.6.30-rc6_scsi-
> misc_irqf-d
> 68.1402 <database> 66.1875 <database>
> 0.9125 qla24xx_start_scsi 0.9552 qla24xx_start_scsi
> 0.8729 __schedule 0.9272 __schedule
> 0.7739 qla24xx_intr_handler 0.9178 qla24xx_intr_handler
> 0.7161 kmem_cache_alloc 0.7963 kmem_cache_alloc
> 0.4686 __sigsetjmp 0.4580 __sigsetjmp
> 0.4043 __blockdev_direct_IO 0.4206 __switch_to
> 0.3894 __switch_to 0.4169 __blockdev_direct_IO
> 0.3878 rb_get_reader_page 0.3907 scsi_request_fn
> 0.3762 task_rq_lock 0.3776 task_rq_lock
> 0.3729 scsi_request_fn 0.3701 rb_get_reader_page
> 0.3696 __list_add 0.3664 __list_add
> 0.3168 <bash> 0.3664 copy_user_generic_string
> 0.3135 try_to_wake_up 0.3122 lock_timer_base
> 0.2921 ring_buffer_consume 0.2972 ring_buffer_consume
> 0.2822 lock_timer_base 0.2879 <bash>
> 0.2624 memset_c 0.2785 aio_complete
> 0.2607 aio_complete 0.2524 blk_queue_end_tag
> 0.2508 copy_user_generic_string 0.2468 try_to_wake_up
> 0.2294 qla2x00_process_completed_re 0.2430 tcp_sendmsg
> 0.2294 tcp_sendmsg 0.2393 mod_timer
> 0.2211 kfree 0.2374
> qla2x00_process_completed_re
> 0.2195 memmove 0.2355 memset_c
> 0.2195 blk_queue_end_tag 0.2225 e1000_xmit_frame
> 0.2145 scsi_softirq_done 0.2094 generic_make_request
> 0.2145 mod_timer 0.2075 scsi_device_unbusy
> 0.2129 generic_file_aio_read 0.2056 kref_get
> 0.2096 kref_get 0.2056 mempool_free
> 0.1997 e1000_xmit_frame 0.2038 qla2xxx_queuecommand
> 0.1997 scsi_device_unbusy 0.2000 kfree