Re: [f2fs-dev] [PATCH 2/2] f2fs: handle decompress only post processing in softirq

From: Gao Xiang
Date: Mon Jun 20 2022 - 20:58:16 EST


On Mon, Jun 20, 2022 at 10:38:43AM -0700, Daeho Jeong wrote:
> From: Daeho Jeong <daehojeong@xxxxxxxxxx>
>
> Now decompression is being handled in workqueue and it makes read I/O
> latency non-deterministic, because of the non-deterministic scheduling
> nature of workqueues. So, I made it handled in softirq context only if
> possible, not in low memory devices, since this modification will
> maintain decompresion related memory a little longer.
>

Again, I don't think this method scalable. Since you already handle
all decompression algorithms in this way. Laterly, I wonder if you'd
like to handle all:
- decompression algorithms;
- verity algorithms;
- decrypt algorithms;

in this way, regardless of slow decompression algorithms, that would be a
long latency and CPU overhead of softirq context. This is my last words
on this, I will not talk anymore.

Thanks,
Gao Xiang