[RFC PATCH 2/2] arm64: Implement vmalloc based thread_info allocator
arnd at arndb.de
Sun May 24 10:49:01 PDT 2015
On Monday 25 May 2015 01:02:20 Jungseok Lee wrote:
> Fork-routine sometimes fails to get a physically contiguous region for
> thread_info on 4KB page system although free memory is enough. That is,
> a physically contiguous region, which is currently 16KB, is not available
> since system memory is fragmented.
> This patch tries to solve the problem as allocating thread_info memory
> from vmalloc space, not 1:1 mapping one. The downside is one additional
> page allocation in case of vmalloc. However, vmalloc space is large enough,
> around 240GB, under a combination of 39-bit VA and 4KB page. Thus, it is
> not a big tradeoff for fork-routine service.
vmalloc has a rather large runtime cost. I'd argue that failing to allocate
thread_info structures means something has gone very wrong.
Can you describe the scenario that leads to fragmentation this bad?
Could the stack size be reduced to 8KB perhaps?
More information about the linux-arm-kernel