> I found that genalloc is very slow for large chunk sizes because > bitmap_find_next_zero_area has to grind through that entire bitmap. > Hence, I recommend avoiding genalloc for large chunk sizes.
Thanks for the feedback Daniel! We have been doing 16GiB without any noticeable issues. > I'm thinking how this would behave on a 32 bit ARM platform I don’t think people would be doing such big allocations on 32 bit (ARM systems). It would not make sense for them to be doing >4GB anyway. >> --- a/lib/genalloc.c >> +++ b/lib/genalloc.c >> @@ -194,7 +194,7 @@ int gen_pool_add_virt(struct gen_pool *pool, unsigned >> long virt, phys_addr_t phy >> chunk->phys_addr = phys; >> chunk->start_addr = virt; >> chunk->end_addr = virt + size - 1; >> - atomic_set(&chunk->avail, size); >> + atomic64_set(&chunk->avail, size); > Isn't size defined as a size_t type which is 32 bit wide on ARM? How > can you ever set chunk->avail to anything larger than 2^32 - 1? I did consider changing this type but it seems like there would never be a need to set this value to more than 4GiB on 32 bit systems. >> @@ -464,7 +464,7 @@ size_t gen_pool_avail(struct gen_pool *pool) >> >> rcu_read_lock(); >> list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) >> - avail += atomic_read(&chunk->avail); >> + avail += atomic64_read(&chunk->avail); > >avail is defined as size_t (32 bit). Aren't you going to overflow that >variable? Again, I don’t think people on 32 bit systems will be doing >4GB assignments so it would not be an issue. Stephen
