Direct dispatch would be great for geli, especially that geli can use own
(multiple) threads when necessary (eg. using crypto cards). With AES-NI you
could go straight to the disk.
--
Paweł Jakub Dawidek
> On Jul 3, 2020, at 13:22, Alan Somers <asom...@freebsd.org> wrote:
>
> I don't. What I meant was that a single thread (geom) is limiting the
> performance of the system overall. I'm certain, based on top, gstat, and
> zpool iostat, that geom is the limiting factor on this system.
> -Alan
>
>> On Fri, Jul 3, 2020 at 2:18 PM Paweł Jakub Dawidek <pa...@dawidek.net>
>> wrote:
>>
>> Hi Alan,
>>
>> why do you think it will hurt single-threaded performance?
>>
>> --
>> Paweł Jakub Dawidek
>>
>>
>>
>>>> On Jul 3, 2020, at 12:30, Alan Somers <asom...@freebsd.org> wrote:
>>>
>>> I'm using geli, gmultipath, and ZFS on a large system, with hundreds of
>>> drives. What I'm seeing is that under at least some workloads, the
>> overall
>>> performance is limited by the single geom kernel process. procstat and
>>> kgdb aren't much help in telling exactly why this process is using so
>> much
>>> CPU, but it certainly must be related to the fact that over 15,000 IOPs
>> are
>>> going through that thread. What can I do to improve this situation?
>> Would
>>> it make sense to enable direct dispatch for geli? That would hurt
>>> single-threaded performance, but probably improve performance for highly
>>> multithreaded workloads like mine.
>>>
>>> Example top output:
>>> PID USERNAME PRI NICE SIZE RES STATE C TIME WCPU COMMAND
>>> 13 root -8 - 0B 96K CPU46 46 82.7H 70.54%
>>> geom{g_down}
>>> 13 root -8 - 0B 96K - 9 35.5H 25.32%
>>> geom{g_up}
>>>
>>> -Alan
>>> _______________________________________________
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>>> https://lists.freebsd.org/mailman/listinfo/freebsd-geom
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>>
>>
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