linux-kernel - Re: [PATCH 0/5] Improve zram writeback performance

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Message-ID: <20240926044129.GE11458@google.com>
Date: Thu, 26 Sep 2024 13:41:29 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Pankaj Raghav <kernel@...kajraghav.com>
Cc: minchan@...nel.org, senozhatsky@...omium.org,
	linux-kernel@...r.kernel.org, axboe@...nel.dk, p.raghav@...sung.com,
	linux-block@...r.kernel.org, gost.dev@...sung.com
Subject: Re: [PATCH 0/5] Improve zram writeback performance

On (23/09/11 15:34), Pankaj Raghav wrote:
> Batching reduces the time of writeback of 4G data to a nvme backing device
> from 68 secs to 15 secs (more than **4x improvement**).

I don't think anyone does that on practice.  Excessive writeback wears
out flash storage, so on practice no one writebacks gigabytes of data
all at once, but instead people put daily writeback limits and try to
be flash storage "friendly", which is especially important if your device
has to a lifespan of 7 or 10 years.  IOW usually writeback is put under
such constraints that writeback speed is hardly noticeable.  So I'm not
sure that the complexity that this patch introduces is justified, to be
honest.