search for: 256x

...les of a wide variety of sizes will be created. At this layer they will be created with variable block sizes (512B to 128K). The implications for a 512 byte write in the upper level zpool (inside a zone or ldom) seems to be: - The 512 byte write turns into a 128 KB write at the storage server (256x multiplication in write size). - To write that 128 KB block, the rest of the block needs to be read to recalculate the checksum. That is, a read/modify/write process is forced. (Less impact if block already in ARC.) - Deduplicaiton is likely to be less effective because it is unlikely that...

...> Hi, > > This is long thread, so I will combine several comments into single email. > > > >> - 8-bit per-thread counters, dumping into central counters on overflow. > >The overflow will happen very quickly with 8bit counter. > > Yes, but it reduces contention by 256x (a thread must execute at least 256 > loop iterations between increments). In practice, if you reduce contention > below some threshold, it does not represent a problem anymore. > > > > >> - per-thread counters. Solves the problem at huge cost in RAM per-thread > >It i...

...> Hi, > > This is long thread, so I will combine several comments into single email. > > > >> - 8-bit per-thread counters, dumping into central counters on overflow. > >The overflow will happen very quickly with 8bit counter. > > Yes, but it reduces contention by 256x (a thread must execute at least 256 > loop iterations between increments). In practice, if you reduce contention > below some threshold, it does not represent a problem anymore. > > > > >> - per-thread counters. Solves the problem at huge cost in RAM per-thread > >It i...

On Apr 17, 2014, at 2:04 PM, Chandler Carruth <chandlerc at google.com> wrote: > On Thu, Apr 17, 2014 at 1:27 PM, Justin Bogner <mail at justinbogner.com> wrote: > Chandler Carruth <chandlerc at google.com> writes: > > if (thread-ID != main's thread-ID && shard_count < std::min(MAX, NUMBER_OF_CORES)) { > > shard_count = std::min(MAX,

...gt;>> >>>> >>>>>> - 8-bit per-thread counters, dumping into central counters on >>>>>> overflow. >>>>> The overflow will happen very quickly with 8bit counter. >>>> >>>> Yes, but it reduces contention by 256x (a thread must execute at least >>>> 256 loop iterations between increments). In practice, if you reduce >>>> contention below some threshold, it does not represent a problem anymore. >>>> >>>> >>>> >>>>>> - per-thread...

...Hi, > > This is long thread, so I will combine several comments into single email. > > > >> - 8-bit per-thread counters, dumping into central counters on overflow. > >The overflow will happen very quickly with 8bit counter. > > Yes, but it reduces contention by 256x (a thread must execute at least 256 loop iterations between increments). In practice, if you reduce contention below some threshold, it does not represent a problem anymore. > > > > >> - per-thread counters. Solves the problem at huge cost in RAM per-thread > >It is not p...

...into single >>> email. >>> >>> >>> >> - 8-bit per-thread counters, dumping into central counters on >>> overflow. >>> >The overflow will happen very quickly with 8bit counter. >>> >>> Yes, but it reduces contention by 256x (a thread must execute at least >>> 256 loop iterations between increments). In practice, if you reduce >>> contention below some threshold, it does not represent a problem anymore. >>> >>> >>> >>> >> - per-thread counters. Solves the prob...