Hi Dmitry, On 2022/10/11 23:58, Dmitry Kozlyuk wrote: > 2022-10-11 12:17 (UTC+0000), Chengwen Feng: >> This patch adds a memarea backup mechanism, where an allocation request >> which cannot be met by the current memarea is deferred to its backup >> memarea. > > This is a controversial feature. > > 1. It violates memarea property of freeing all allocated objects > at once when the memarea itself is destroyed. Objects allocated > in the backup memarea through the destroyed one will remain. > > 2. If there was an API to check that the object belongs to a memarea > (the check from rte_memarea_update_refcnt() in this patch), > it would be trivial to implement this feature on top of memarea API.
This patch add 'struct memarea *owner' in each object's meta data, and it was used to free which allocated from backup memarea. So this problem will not exist. > > Nit: "Deferred" is about time -> "forwarded", "delegated", or "handled over". ok > > A general note about this series. > IMO, libraries should have limited scope and allow composition > rather than accumulate features and control their use via options. > The core idea of memarea is an allocator within a memory region, > a fast one and with low overhead, usable to free all objects at once. > > This is orthogonal to the question from where the memory comes from. > HEAP and LIBC sources could be built on top of USER source, > which means that the concept of source is less relevant. > Backup mechanism could instead be a way to add memory to the area, > in which case HEAP and LIBC memarea would also be expandable. > Memarea API could be defined as a structure with callbacks, > and different types of memarea could be combined, > for example, interlocked memarea on top of expandable memarea on top of > memarea with a particular memory management algorithm. > > I'm not saying we should immediately build all this complexity. > On the contrary, I would merge the basic things first, > then try to _stack_ new features on top, > then look if interfaces emerge that can be used for composition. Agree, I will drop this feature in next version. > . >
