[Gluster-devel] Throttling xlator on the bricks

[Joe Julian]

On 01/25/16 18:24, Ravishankar N wrote:
>
> On 01/26/2016 01:22 AM, Shreyas Siravara wrote:
>> Just out of curiosity, what benefits do we think this throttling 
>> xlator would provide over the "enable-least-priority" option (where 
>> we put all the fops from SHD, etc into a least pri queue)?
>>
>
> For one, it could provide more granularity on the amount of throttling 
> you want to do, for specific fops, from specific clients. If the only 
> I/O going through the bricks was from the SHD, they would all be 
> least-priority but yet consume an unfair % of the CPU. We could tweak 
> `performance.least-rate-limit` to throttle but it would be a global 
> option.

Right, because as it is now, when shd is the only client, it queues up 
so much iops that higher prioritiy ops are still getting delayed.

>
>
>>> On Jan 25, 2016, at 12:29 AM, Venky Shankar <vshankar at redhat.com> 
>>> wrote:
>>>
>>> On Mon, Jan 25, 2016 at 01:08:38PM +0530, Ravishankar N wrote:
>>>> On 01/25/2016 12:56 PM, Venky Shankar wrote:
>>>>> Also, it would be beneficial to have the core TBF implementation 
>>>>> as part of
>>>>> libglusterfs so as to be consumable by the server side xlator 
>>>>> component to
>>>>> throttle dispatched FOPs and for daemons to throttle anything 
>>>>> that's outside
>>>>> "brick" boundary (such as cpu, etc..).
>>>> That makes sense. We were initially thinking to overload 
>>>> posix_rchecksum()
>>>> to do the SHA256 sums for the signer.
>>> That does have advantages by avoiding network rountrips by computing 
>>> SHA* locally.
>>> TBF could still implement ->rchecksum and throttle that (on behalf 
>>> of clients,
>>> residing on the server - internal daemons). Placing the core 
>>> implementation as
>>> part of libglusterfs would still provide the flexibility.
>>>
>>>>
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>
>
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