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From: Arjan van de Ven <arjanvandeven@gmail.com>
Date: Fri, 17 Jun 2016 07:26:08 -0700
Message-ID: <CADyApD2uUOasqiiX4Tvsqqpg6M0yhaFr_tmGn0pcT1OsRJqq8Q@mail.gmail.com>
Subject: Re: [patch V2 00/20] timer: Refactor the timer wheel
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Eric Dumazet <edumazet@google.com>,
        Frederic Weisbecker <fweisbec@gmail.com>, Chris Mason <clm@fb.com>,
        Arjan van de Ven <arjan@infradead.org>, rt@linutronix.de,
        Rik van Riel <riel@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        George Spelvin <linux@sciencehorizons.net>,
        Len Brown <lenb@kernel.org>
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>    To achieve this capacity with HZ=1000 without increasing the storage size
>    by another level, we reduced the granularity of the first wheel level from
>    1ms to 4ms. According to our data, there is no user which relies on that
>    1ms granularity and 99% of those timers are canceled before expiry.


the only likely problem cases are msleep(1) uses... but we could just
map those to usleep(1000,2000)

(imo we should anyway)