[dm-devel] [PATCH 08/12] libmultipath: wait one seconds for more uevents in uevent_listen() in uevents burst situations

[tang.junhui at zte.com.cn]

Hi Martin,

Thank you for your respond, I will modify it and resend it later.

Regards,
Tang



发件人:         Martin Wilck <mwilck at suse.com>
收件人:         tang.junhui at zte.com.cn, christophe.varoqui at opensvc.com, 
hare at suse.de, bmarzins at redhat.com, bart.vanassche at sandisk.com, 
抄送:   dm-devel at redhat.com, zhang.kai16 at zte.com.cn, 
tang.wenjun3 at zte.com.cn
日期:   2016/12/29 04:26
主题:   Re: [PATCH 08/12] libmultipath: wait one seconds for more uevents 
in uevent_listen() in uevents burst situations



On Tue, 2016-12-27 at 16:03 +0800, tang.junhui at zte.com.cn wrote:
> From: tang.junhui <tang.junhui at zte.com.cn>
> 
> The more uevents are merged, the higher efficiency program will
> performs.
> So, do not process uevents after receiving immediately in uevents
> burst
> situations, but continue wait 1 seconds for more uevents except that
> too
> much uevents (2048) have already been received or too much time
> eclipse
> (60 seconds).

Hi Tang,

thanks for this impressive patch set. While I haven't had time to read
through the more complex parts yet, one small nitpick on this patch:
please use named constants rather than explicit numbers in the code.

Regards,
Martin


> 
> Change-Id: I763d491540e8114a81d12d603281540a81502742
> Signed-off-by: tang.junhui <tang.junhui at zte.com.cn>
> ---
>  libmultipath/uevent.c | 35 +++++++++++++++++++++++++++++++++--
>  1 file changed, 33 insertions(+), 2 deletions(-)
> 
> diff --git a/libmultipath/uevent.c b/libmultipath/uevent.c
> index cc10d65..b0b05e9 100644
> --- a/libmultipath/uevent.c
> +++ b/libmultipath/uevent.c
> @@ -39,6 +39,7 @@
>  #include <linux/netlink.h>
>  #include <pthread.h>
>  #include <sys/mman.h>
> +#include <sys/time.h>
>  #include <libudev.h>
>  #include <errno.h>
>  
> @@ -490,11 +491,37 @@ struct uevent *uevent_from_udev_device(struct
> udev_device *dev)
>                return uev;
>  }
>  
> +bool uevent_burst(struct timeval *start_time, int events)
> +{
> +              struct timeval diff_time, end_time;
> +              unsigned long speed;
> +              unsigned long eclipse_ms;
> +
> +              gettimeofday(&end_time, NULL);
> +              timersub(&end_time, start_time, &diff_time);
> +
> +              eclipse_ms = diff_time.tv_sec * 1000 + diff_time.tv_usec 
/
> 1000;
> +              if (eclipse_ms == 0)
> +                              return true;
> +              /* max wait 60s */
> +              if (eclipse_ms > 60*1000) {
> +                              condlog(1, "burst continued =%lu ms, 
stoped",
> eclipse_ms);
> +                              return false;
> +              }
> +
> +              speed = (events * 1000) / eclipse_ms;
> +              if (speed > 10)
> +                              return true;
> +
> +              return false;
> +}
> +
>  int uevent_listen(struct udev *udev)
>  {
>                int err = 2;
>                struct udev_monitor *monitor = NULL;
>                int fd, socket_flags, events;
> +              struct timeval start_time;
>                int need_failback = 1;
>                int timeout = 30;
>                LIST_HEAD(uevlisten_tmp);
> @@ -548,6 +575,7 @@ int uevent_listen(struct udev *udev)
>                }
>  
>                events = 0;
> +              gettimeofday(&start_time, NULL);
>                while (1) {
>                                struct uevent *uev;
>                                struct udev_device *dev;
> @@ -562,7 +590,8 @@ int uevent_listen(struct udev *udev)
>                                errno = 0;
>                                fdcount = poll(&ev_poll, 1, 
poll_timeout);
>                                if (fdcount && ev_poll.revents & POLLIN) 
{
> -                                              timeout = 0;
> +                                              timeout = 
uevent_burst(&start_time, events +
> 1) ? 1:0;
> +
>                                                dev = 
udev_monitor_receive_device(monitor);
>                                                if (!dev) {
>   condlog(0, "failed getting udev
> device");
> @@ -578,7 +607,8 @@ int uevent_listen(struct udev *udev)
>                                                }
>                                                list_add_tail(&uev->node, 
&uevlisten_tmp);
>                                                events++;
> -                                              continue;
> +                                              if(events < 2048)
> +                                                              continue;
>                                }
>                                if (fdcount < 0) {
>                                                if (errno == EINTR)
> @@ -600,6 +630,7 @@ int uevent_listen(struct udev *udev)
>   pthread_mutex_unlock(uevq_lockp);
>                                                events = 0;
>                                }
> +                              gettimeofday(&start_time, NULL);
>                                timeout = 30;
>                }
>                need_failback = 0;

-- 
Dr. Martin Wilck <mwilck at suse.com>, Tel. +49 (0)911 74053 2107
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)



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