> -----Original Message----- > From: Liu Yuan [mailto:[email protected]] > Sent: Monday, March 26, 2012 6:08 PM > To: huxinwei > Cc: MORITA Kazutaka; [email protected] > Subject: Re: [Sheepdog] [PATCH v5 4/8] sheep: teach sheep to use object cache > > On 03/26/2012 05:26 PM, huxinwei wrote: > > > My point is about _different_ VMs reading the same object. > > It doesn't matter how you optimize guest here ... > > > We can't read the same object from mutiple VMs right now. (Farm > originally supports naming the object by hash content for data > deduplication)
We can, if these VMs are actually cloned from the same snapshot ;) BTW: I'm not aware that you are planning data dedup already for farm. That'll be really awesome ;) However, 4M is far too big for effective deduplication, IMHO. It seems we need a patch to change the size of object, e.g. 128K as ZFS. > If we do, yes, in this scenario, we would benefit some workloads (mostly > read, seldom write) from a unified and content-named cache. > But for a general cache, if we have a unified cache (be it in memory or > on disk) that serve a lot of VM requests concurrently, I think we would > meet the lock contention problem, hardly to be scalable. Agreed. > So we might later have a unified cache complementarity(a transparent > write through cache) in memory for this kind of read acceleration on top > of object cache, which just aims to be generally reducing the network > traffic by absorbing IO requests locally. > > Thanks, > Yuan -- sheepdog mailing list [email protected] http://lists.wpkg.org/mailman/listinfo/sheepdog
