On 25.08.25 14:29, wangyufei wrote:
Hi everyone,
We've been interested in this patch about parallelizing writeback [1]
and have been following its discussion and development. Our testing in
several application scenarios on mobile devices has shown significant
performance improvements.
Currently, we're focusing on how the number of writeback contexts impacts
the performance on different filesystems and storage workloads. We noticed
the previous discussion about making the number of writeback contexts an
opt-in configuration to adapt to different filesystems [2]. Currently, it
can only be set via a sysfs interface at system initialization. We'd like
to discuss the possibility of supporting dynamic runtime configuration of
the number of writeback contexts.
We have developed a mechanism that allows the number of writeback contexts
to be configured at runtime via a sysfs interface. To configure, use:
echo <nr_wb_ctx> > /sys/class/bdi/<dev>/nwritebacks.
What's the target use case for updating it dynamically?
If it's mostly for debugging/testing (find out what works, what
doesn't), it might better go into debugfs or just carried out of tree.
If it's about setting sane default based on specific filesystems, maybe
it could be optimized from within the kernel, without the need to expose
this to an admin?
--
Cheers
David / dhildenb
