I was not watching the hash build process of the collection of structure Part, and i think the method proposed need to be improved.
On Tue, Mar 15, 2011 at 11:06 AM, 张练 <wahu0315...@gmail.com> wrote: > In https://cwiki.apache.org/TS/ssdsupport.html, we proposed our > demands. > In irc log jplevyakg proposed three ways for supporting ssd cache. > 1) attach to the RAM cache to store the objects. That would be lower > CPU and would lean hard on the SSD and would use RAM to get a decent > replacement policy 2) attach to the disk as a front end cache. Again lower > CPU but use less RAM and have a poorer replacement policy. Or 3) go for > full priority queue, best replacement policy, most flexibly, but also the > most work and potentially use more CPU and a go > I was thinking the second option, i wanna select ssd as a transition > cache in sata and ram cache. > 1) When an user request arrived, ts first find it in ram cache, if not > hit, then ssd, and then sata. > 2) When the request was hit in ram cache or ssd, then return the object > to the user. When the request was hit in sata, then write it to ram cache > following the existing way, at the same time write it to ssd also. When the > request was not hit in all the cache, then the request was send to origin > server, and write the object back to sata.(Because our cache hierachy was > 10G ram cache+100G ssd+1TB sata, so write request both in ram cache and ssd > waste at most 10% percent storage) > I reviewed the Part structure, and i think i can use Part for > supporting ssd cache. I wanna keep a special Part member in Cache, and when > Cache find an object, it first find it in ram cache, and if not hit, then > find it in this special Part member, and then the CacheHostTable member. > Because i don't wanna ts do two asynchronous read, so i wanna find the right > Part and do only one read. If not so, i thought there maybe two asynchronous > read: first find in ssd cache, and if false, go to sata. This will also > change the logic of do_cache_open_read and state_cache_open_read in > HttpCacheSM. > I have seen the codes of iocore/cache for 2 weeks, but i think if i > want to understand it fully, i need another serveral weeks based on some > help. If you have a better scheme, please tell me. Right now i have to find > the fast way to support ssd asap, because we wanna to put ATS to online > usage. I have not seen the codes related with partition.config and > hosting.config, and i think if let ssd cache works with partition.config, > then another more work will be done, that will delay our plan. But the best > thing i wanna do is to implement it in an general patch for others' usage, > so i wanna find a better scheme, and do some work for current demands, and > later, complete another more demands. > > -- > Best regards, > Lian Zhang > > -- Best regards, Lian Zhang
