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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Alexander Duyck <alexander.duyck@gmail.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	sridhar.samudrala@intel.com, edumazet@google.com,
	davem@davemloft.net, linux-api@vger.kernel.org
Subject: Re: [net-next PATCH v2 5/8] net: Track start of busy loop instead of when it should end
Date: Thu, 23 Mar 2017 18:24:42 -0700	[thread overview]
Message-ID: <1490318682.9687.22.camel@edumazet-glaptop3.roam.corp.google.com> (raw)
In-Reply-To: <20170323213742.12615.85793.stgit@localhost.localdomain>

On Thu, 2017-03-23 at 14:37 -0700, Alexander Duyck wrote:
> From: Alexander Duyck <alexander.h.duyck@intel.com>
> 

> The last bit I changed is to move from using a shift by 10 to just using
> NSEC_PER_USEC and using multiplication for any run time calculations and
> division for a few compile time ones.  This should be more accurate and
> perform about the same on most architectures since modern CPUs typically
> handle multiplication without too much overhead.


busy polling thread can be preempted for more than 2 seconds.

Using usec instead of nanoseconds gave us 3 orders of magnitude cushion.

We do not need nsec accuracy for busy polling users, if this restricts
range and usability under stress.

  reply	other threads:[~2017-03-24  1:24 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-23 21:36 [net-next PATCH v2 0/8] Add busy poll support for epoll Alexander Duyck
2017-03-23 21:36 ` [net-next PATCH v2 1/8] net: Busy polling should ignore sender CPUs Alexander Duyck
2017-03-23 22:05   ` Eric Dumazet
2017-03-23 21:36 ` [net-next PATCH v2 2/8] tcp: Record Rx hash and NAPI ID in tcp_child_process Alexander Duyck
2017-03-24  1:00   ` Eric Dumazet
2017-03-23 21:36 ` [net-next PATCH v2 3/8] net: Only define skb_mark_napi_id in one spot instead of two Alexander Duyck
2017-03-24  1:02   ` Eric Dumazet
2017-03-23 21:37 ` [net-next PATCH v2 4/8] net: Change return type of sk_busy_loop from bool to void Alexander Duyck
2017-03-24  1:02   ` Eric Dumazet
2017-03-23 21:37 ` [net-next PATCH v2 5/8] net: Track start of busy loop instead of when it should end Alexander Duyck
2017-03-24  1:24   ` Eric Dumazet [this message]
2017-03-24  3:42     ` Alexander Duyck
2017-03-24  4:27       ` Eric Dumazet
2017-03-24  4:38         ` Eric Dumazet
2017-03-24  5:55         ` Alexander Duyck
2017-03-24 11:16           ` Eric Dumazet
2017-03-24 15:48             ` Alexander Duyck
2017-03-23 21:37 ` [net-next PATCH v2 6/8] net: Commonize busy polling code to focus on napi_id instead of socket Alexander Duyck
2017-03-23 22:25   ` Eric Dumazet
2017-03-23 21:37 ` [net-next PATCH v2 7/8] epoll: Add busy poll support to epoll with socket fds Alexander Duyck
2017-03-23 21:38 ` [net-next PATCH v2 8/8] net: Introduce SO_INCOMING_NAPI_ID Alexander Duyck
2017-03-23 22:22   ` Eric Dumazet
2017-03-23 22:43   ` Andy Lutomirski
2017-03-24  0:58     ` Alexander Duyck
2017-03-24  4:47       ` Andy Lutomirski
2017-03-24  5:07         ` Eric Dumazet
2017-03-23 22:07 ` [net-next PATCH v2 0/8] Add busy poll support for epoll Alexei Starovoitov
2017-03-23 22:38   ` Alexander Duyck
2017-03-23 22:49     ` Eric Dumazet

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