On 17/03/2015 08:52, Xinze Chi wrote: > ---------- Forwarded message ---------- > From: Xinze Chi <xmdxcxz@xxxxxxxxx> > Date: 2015-03-17 15:52 GMT+08:00 > Subject: Re: Fwd: Reduce read latency and bandwidth for ec pool > To: Loic Dachary <loic@xxxxxxxxxxx> > > > Yes, In my VDI environment, client read 4k every time. If we can read > object from only shard. It would reduce the latency and bandwidth a > lot. I'm curious about your workload. Are you using RadosGW ? RBD ? > Thanks. > > 2015-03-17 15:48 GMT+08:00 Loic Dachary <loic@xxxxxxxxxxx>: >> Hi, >> >> On 17/03/2015 08:27, Xinze Chi wrote: >>> hi, loic: >>> >>> I have an idea which could reduce read latency and bandwidth for ec pool. >>> >>> But, I don't know whether it is feasible. >>> >>> Such as ec pool stripe_width = 16384 = 4 * 4096, K = 4, M =2 >>> >>> So ceph will partition the total of 16384 bytes to 4 data chunk, >>> and encoding 2 parity chunk >>> >>> shard_0 include 0 - (4096-1) in original data; >>> shard_1 include 4096 - (4096*2 - 1) in original data; >>> shard_2 include 4096*2 - (4096 * 3 -1) in original data; >>> shard_3 include 4096*3 - (4096 * 4 - 1) in original data >>> shard_4 include parity chunk >>> shard_5 include parity chunk >>> >>> Now if client read (offset 0, len 4096) from object, it should >>> read 4 shard (from 0-3) and decode all this 4 chunk. >>> >>> But, this example, maybe we can compute the destination shard >>> based on ec pool config ,read offset and read len , we only read >>> >>> shard_0 and return it to client, because shard_0 has include all data >>> as client need. >> >> That optimization makes sense to me. I guess you're interested in having small objects in the pool and only read a few bytes at a time ? >> >> Cheers >> >>> >>> Wait for your comment. >>> >>> Thanks. >>> >> >> -- >> Loïc Dachary, Artisan Logiciel Libre >> > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- Loïc Dachary, Artisan Logiciel Libre
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