Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <cabd732a-9942-3ece-8141-c0bc6378faca@acm.org>
Date:   Fri, 22 Jul 2022 11:12:38 -0700
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.11.0
Subject: Re: [dm-devel] [PATCH 0/3] dm-verity: optionally use tasklets in
 dm-verity
Content-Language: en-US
To:     Christoph Hellwig <hch@infradead.org>,
        Nathan Huckleberry <nhuck@google.com>
Cc:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Mike Snitzer <snitzer@kernel.org>,
        linux-kernel@vger.kernel.org, Eric Biggers <ebiggers@kernel.org>,
        dm-devel@redhat.com, Sami Tolvanen <samitolvanen@google.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Alasdair Kergon <agk@redhat.com>
References: <20220722093823.4158756-1-nhuck@google.com>
 <YtrTI/CJMoLihA/1@infradead.org>
From:   Bart Van Assche <bvanassche@acm.org>
In-Reply-To: <YtrTI/CJMoLihA/1@infradead.org>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 7/22/22 09:41, Christoph Hellwig wrote:
> We've been tying to kill off task lets for about 15 years.  I don't
> think adding new users will make you a whole lot of friends..

+1 for not using tasklets. At least in Android the real-time thread 
scheduling latency is important. Tasklets are not visible to the 
scheduler and hence cause latency spikes for real-time threads. These 
latency spikes can be observed by users, e.g. if the real-time thread is 
involved in audio playback.

Bart.