linux-kernel - Re: [RFC PATCH 0/1] dm-crypt excessive overhead

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Message-ID: <20200624002301.GB12716@gondor.apana.org.au>
Date:   Wed, 24 Jun 2020 10:23:01 +1000
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Ignat Korchagin <ignat@...udflare.com>
Cc:     Mike Snitzer <snitzer@...hat.com>,
        Mikulas Patocka <mpatocka@...hat.com>,
        "David S. Miller" <davem@...emloft.net>, agk@...hat.com,
        dm-devel@...hat.com, dm-crypt@...ut.de,
        linux-kernel <linux-kernel@...r.kernel.org>,
        kernel-team <kernel-team@...udflare.com>
Subject: Re: [RFC PATCH 0/1] dm-crypt excessive overhead

On Tue, Jun 23, 2020 at 05:24:39PM +0100, Ignat Korchagin wrote:
> 
> I may be misunderstanding the terminology, but tasklets execute in
> soft IRQ, don't they? What we care about is to execute the decryption
> as fast as possible, but we can't do it in a hard IRQ context (that
> is, the interrupt context where other interrupts are disabled). As far
> as I understand, tasklets are executed right after the hard IRQ
> context, but with interrupts enabled - which is the first safe-ish
> place to do more lengthy processing without the risk of missing an
> interrupt.

Yes you are absolutely right.  In general high-performance work
should be carried out in softirq context.  That's how the networking
stack works for example.

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt