[ceph-users] Re: mclock and massive reads

2024-03-28 Thread Luis Domingues





Luis Domingues
Proton AG


On Thursday, 28 March 2024 at 10:10, Sridhar Seshasayee  
wrote:

> Hi Luis,
> 
> > So our question, is mClock taking into account the reads as well as the
> > writes? Or are the reads calculate to be less expensive than the writes?
> 
> mClock treats both reads and writes equally. When you say "massive reads",
> do you mean a predominantly
> read workload? Also, the size of the reads is also factored in to arrive at
> the cost of the operation. In general,
> the cost of an I/O operation in mClock is proportional to its size. The
> higher the cost, the longer the operation
> stays in the queue. That being said, the implementation of mClock on
> pacific is experimental at best. I would
> recommend upgrading to either quincy or reef considering the significant
> improvements that were made both
> in terms of scheduling and usability.
> 
> -Sridhar
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> ceph-users mailing list -- ceph-users@ceph.io
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When I say massive reads, is when we are draining a disk or a node. Outside of 
that particular use case, everything works quite well.

We plan upgrading in a near future, so we will see.
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[ceph-users] Re: mclock and massive reads

2024-03-28 Thread Sridhar Seshasayee
Hi Luis,


> So our question, is mClock taking into account the reads as well as the
> writes? Or are the reads calculate to be less expensive than the writes?
>
>
mClock treats both reads and writes equally. When you say "massive reads",
do you mean a predominantly
read workload? Also, the size of the reads is also factored in to arrive at
the cost of the operation. In general,
the cost of an I/O operation in mClock is proportional to its size. The
higher the cost, the longer the operation
stays in the queue. That being said, the implementation of mClock on
pacific is experimental at best. I would
recommend upgrading to either quincy or reef considering the significant
improvements that were made both
in terms of scheduling and usability.

-Sridhar
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