lkml.org 
[lkml]   [2017]   [Aug]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 00/25] hrtimer: Provide softirq context hrtimers
    I'm sorry for the typo in the email address!

    Anna-Maria

    On Thu, 31 Aug 2017, Anna-Maria Gleixner wrote:

    > There are quite some places in the kernel which use a combination of
    > hrtimers and tasklets to make use of the precise expiry of hrtimers, which
    > schedule a tasklet to bring the actual function into softirq context.
    >
    > This was introduced when the previous hrtimer softirq code was
    > removed. That code was implemented by expiring the timer in hard irq
    > context and then deferring the execution of the callback into softirq
    > context. That caused a lot of pointless shuffling between the rbtree and a
    > linked list.
    >
    > In recent discussions it turned out that more potential users of hrtimers
    > in softirq context might come up. Aside of that the RT patches need this
    > functionality as well to defer hrtimers into softirq context if their
    > callbacks are not interrupt safe on RT.
    >
    > This series implements a new approach by adding SOFT_* clock ids and
    > instead of doing the list shuffle, timers started with these clock ids are
    > put into separate soft expiry hrtimer queues. These queues are evaluated
    > only when the hardirq context detects that the first expiring timer in the
    > softirq queues has expired. That makes the overhead in the hardirq context
    > minimal.
    >
    > The series reworks the code to reuse as much as possible from the existing
    > facilities for the new softirq hrtimers and integrates them with all
    > flavours of hrtimers (HIGH_RES=y/n - NOHZ=y/n).
    >
    > To achieve this quite some of the conditionals in the existing code are
    > removed for the price of adding some pointless data and state tracking to
    > the HIGH_RES=n case. That's minimal, but well worth it as it increases the
    > readability and maintainability of the code.
    >
    > The first part of the series implements the new functionality and the
    > second part converts the hrtimer/tasklet users to make use of it and
    > removes struct hrtimer_tasklet and the surrounding helper functions.
    >
    > This series is available from git as well:
    >
    > git://git.kernel.org/pub/scm/linux/kernel/git/bigeasy/linux-hrtimer.git soft_hrtimer
    > https://git.kernel.org/bigeasy/linux-hrtimer/h/soft_hrtimer
    >
    >
    > Thanks,
    >
    > Anna-Maria
    >
    > ---
    > drivers/net/usb/cdc_ncm.c | 37 +-
    > drivers/net/wireless/mac80211_hwsim.c | 44 +-
    > drivers/usb/gadget/function/f_ncm.c | 28 -
    > include/linux/hrtimer.h | 76 ++---
    > include/linux/interrupt.h | 25 -
    > include/linux/usb/cdc_ncm.h | 2
    > include/net/xfrm.h | 2
    > kernel/softirq.c | 51 ---
    > kernel/time/hrtimer.c | 513 +++++++++++++++++++++-------------
    > net/can/bcm.c | 150 +++------
    > net/xfrm/xfrm_state.c | 29 +
    > sound/drivers/dummy.c | 16 -
    > 12 files changed, 484 insertions(+), 489 deletions(-)
    >
    >

    \
     
     \ /
      Last update: 2017-08-31 14:36    [W:6.238 / U:0.032 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site