On 3/11/21 8:04 PM, Konstantin Belousov wrote:
On Thu, Mar 11, 2021 at 07:41:53PM +0100, Hans Petter Selasky wrote:
On 3/11/21 7:35 PM, Konstantin Belousov wrote:
And I dislike this. It is yet another case of introducing consumer-specific
logic into core. Isn't netepoch example enough?
I presented another patch to Hans, where task and mm allocations are
switched to zones, and the zones have reserve applied. Then allocations
from ithreads use the reserve.
There is one detail there, reserve is finite, for x86 I set it to the
total limit of interrupts. This somewhat breaks if interrupts are
deallocated and reallocated, but I think it is good enough even with
this wart.
Hi,
Your patch doesn't address the issue of initializing the pointers in
question once. Still, for every call, we need to check if the pointer is
valid. This is not neccessary.
I do not understand what you are saying there.
Which pointers? How does it not address?
Hi,
The current code calls linux_set_current() for every interrupt and timer
callback. That means we continue to check td_lkpi_task for NULL for
every one of these calls. Not strictly needed.
Also I don't see why we need to create a own UMA zone for these simple
structures. Won't the per-CPU sysctl consume more memory than the actual
task structures being allocated?
Dedicated UMA zone allows to gracefully solve the requirement of non-failing
allocation in non-sleepable context. This is much simpler and cleaner than
either trying to enumerate all existing ithreads or adding consumer-specific
controls into generic kernel facility.
Maybe I'm new to UMA zones. The M_USE_RESERVE can also be used with
malloc() ?
--HPS
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