Hi, Brief look to the code give an idea that segment count is different in persistence and in in-memory modes.
I hope someone in the community can approve that this idea is correct. Sincerely, Dmitriy Pavlov пн, 23 июл. 2018 г., 23:46 John Wilson <sami.hailu...@gmail.com>: > I'm talking about PageMemoryNostoreImpl here: > > https://github.com/apache/ignite/blob/ce8e31e28e16c7c22fe88ab6b1a1304b14f6881d/modules/core/src/main/java/org/apache/ignite/internal/pagemem/impl/PageMemoryNoStoreImpl.java#L109 > and > > https://github.com/apache/ignite/blob/ce8e31e28e16c7c22fe88ab6b1a1304b14f6881d/modules/core/src/main/java/org/apache/ignite/internal/pagemem/impl/PageMemoryNoStoreImpl.java#L208 > > Thanks, > > On Thu, Jul 12, 2018 at 10:31 AM, Dmitry Pavlov <dpavlov....@gmail.com> > wrote: > > > Hi, I've double checked code regarding question 1: > > > > PageMemoryImpl#segments segments count (len) comes from sizes array len. > > Sizes array come to page memory from > > GridCacheDatabaseSharedManager.calculateFragmentSizes(). This method > which > > gets availableProcessors from runtime (CPU count). I didn't find any > shift > > to SEG_BITS. > > > > It can be chaged by DataStorageConfiguration.setConcurrencyLevel() but by > > default is the same with #CPU. > > > > Which is why I mentioned segments count = CPU count by default in wiki. > > > > Recenly some member of community proposed update to offical doc about > > segments count. So now it states #segments=#CPU. > > > > So I guess for 8 CPU we will have 8 segments. > > > > Please correct me if I missing something. > > > > Sincerely, > > Dmitriy Pavlov > > > > ср, 27 июн. 2018 г. в 15:30, Eduard Shangareev < > > eduard.shangar...@gmail.com > > >: > > > > > Dmitry, > > > > > > I mean Chugunov, but I have questioned him. His answer was the A. > > Goncharuk > > > should now the answer. > > > > > > On Wed, Jun 27, 2018 at 2:58 PM, Dmitry Pavlov <dpavlov....@gmail.com> > > > wrote: > > > > > > > John, is this question still actual? > > > > > > > > пт, 22 июн. 2018 г. в 15:18, Dmitry Pavlov <dpavlov....@gmail.com>: > > > > > > > > > Hi Ed, > > > > > > > > > > Which Sergey do you mean? I know a number of contributors. > > > > > > > > > > Sincerely, > > > > > > > > > > > > > > > вт, 19 июн. 2018 г. в 22:15, Eduard Shangareev < > > > > > eduard.shangar...@gmail.com>: > > > > > > > > > >> Hi, > > > > >> > > > > >> 1. It looks weird, yeah. Need to ask Sergey, who has changed it > last > > > > time. > > > > >> > > > > >> 2. Because we could reuse memory. For example, after cache destroy > > or > > > > >> something like that. > > > > >> > > > > >> On Tue, Jun 19, 2018 at 9:58 PM, John Wilson < > > sami.hailu...@gmail.com > > > > > > > > >> wrote: > > > > >> > > > > >> > Hi, > > > > >> > > > > > >> > Two quick questions: > > > > >> > > > > > >> > > > > > >> > 1. The design documentation here, > > > > >> > https://cwiki.apache.org/confluence/display/IGNITE/ > > > > >> > Ignite+Durable+Memory+-+under+the+hood, > > > > >> > states that the default segment count is equal to the number > of > > > > >> logical > > > > >> > cores available in the underlying machine. However, the > > segments > > > > >> array > > > > >> > in > > > > >> > PageMemory indicates that the maximum number of segments is: > 1 > > << > > > > >> > SEG_BITS. > > > > >> > Since SEG_BITS = 4, the max # segments is 16. Did I miss > > > something > > > > >> here? > > > > >> > 2. Reading the code in PageMemoryNoStoreImp, it looks like > > pages > > > > are > > > > >> > allocated segment sequentially in a bump-the-pointer strategy > > > where > > > > >> the > > > > >> > first 8 bytes of a segment hold a pointer to the index of the > > > last > > > > >> > allocated page. If this is true, then I don't understand the > > > point > > > > of > > > > >> > having a page map buckets. Why not use a simple arithmetic > > index > > > * > > > > >> > pageSize > > > > >> > to get the offset of a page? > > > > >> > > > > > >> > Thanks. > > > > >> > John > > > > >> > > > > > >> > > > > > > > > > > > > > > >
