From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bruce Richardson Subject: Re: [PATCH v5 18/19] ring: add sched_yield to avoid spin forever Date: Thu, 12 Feb 2015 13:11:37 +0000 Message-ID: <20150212131136.GA14596@bricha3-MOBL3> References: <1422842559-13617-1-git-send-email-cunming.liang@intel.com> <1423728996-3004-1-git-send-email-cunming.liang@intel.com> <1423728996-3004-19-git-send-email-cunming.liang@intel.com> <54DC8B78.2040009@6wind.com> <2601191342CEEE43887BDE71AB977258213E5500@irsmsx105.ger.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "dev-VfR2kkLFssw@public.gmane.org" To: "Ananyev, Konstantin" Return-path: Content-Disposition: inline In-Reply-To: <2601191342CEEE43887BDE71AB977258213E5500-pww93C2UFcwu0RiL9chJVbfspsVTdybXVpNB7YpNyf8@public.gmane.org> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org Sender: "dev" On Thu, Feb 12, 2015 at 01:08:43PM +0000, Ananyev, Konstantin wrote: > > > > -----Original Message----- > > From: Liang, Cunming > > Sent: Thursday, February 12, 2015 1:05 PM > > To: Olivier MATZ; dev-VfR2kkLFssw@public.gmane.org > > Cc: Ananyev, Konstantin > > Subject: RE: [PATCH v5 18/19] ring: add sched_yield to avoid spin forever > > > > Hi, > > > > > -----Original Message----- > > > From: Olivier MATZ [mailto:olivier.matz-pdR9zngts4EAvxtiuMwx3w@public.gmane.org] > > > Sent: Thursday, February 12, 2015 7:16 PM > > > To: Liang, Cunming; dev-VfR2kkLFssw@public.gmane.org > > > Cc: Ananyev, Konstantin > > > Subject: Re: [PATCH v5 18/19] ring: add sched_yield to avoid spin forever > > > > > > Hi, > > > > > > On 02/12/2015 09:16 AM, Cunming Liang wrote: > > > > Add a sched_yield() syscall if the thread spins for too long, waiting other thread > > > to finish its operations on the ring. > > > > That gives pre-empted thread a chance to proceed and finish with ring > > > enqnue/dequeue operation. > > > > The purpose is to reduce contention on the ring. By ring_perf_test, it doesn't > > > shows additional perf penalty. > > > > > > > > Signed-off-by: Cunming Liang > > > > --- > > > > v5 changes: > > > > add RTE_RING_PAUSE_REP to config file > > > > > > > > v4 changes: > > > > update and add more comments on sched_yield() > > > > > > > > v3 changes: > > > > new patch adding sched_yield() in rte_ring to avoid long spin > > > > > > > > config/common_bsdapp | 1 + > > > > config/common_linuxapp | 1 + > > > > lib/librte_ring/rte_ring.h | 31 +++++++++++++++++++++++++++---- > > > > 3 files changed, 29 insertions(+), 4 deletions(-) > > > > > > > > diff --git a/config/common_bsdapp b/config/common_bsdapp > > > > index 57bacb8..52c5143 100644 > > > > --- a/config/common_bsdapp > > > > +++ b/config/common_bsdapp > > > > @@ -234,6 +234,7 @@ CONFIG_RTE_PMD_PACKET_PREFETCH=y > > > > CONFIG_RTE_LIBRTE_RING=y > > > > CONFIG_RTE_LIBRTE_RING_DEBUG=n > > > > CONFIG_RTE_RING_SPLIT_PROD_CONS=n > > > > +CONFIG_RTE_RING_PAUSE_REP=n > > > > > > Maybe it's better to use CONFIG_RTE_RING_PAUSE_REP=0 instead? > > > If I understand well, it has to be set to an integer value to > > > enable it, am I correct? > > [LCM] If RTE_RING_PAUSE_REP=N (no define), by default will use 0. If it's set to 'y'(=1), will issue yield in the most frequent rate. > > It also can set as integer to assign any number. All cases works for this configure. > > One point is in configure file, just demonstrate the default way to use it. > > It can't prevent to use anything unexpected. Except we rule the n & y illegal for this option. > > The meaningful value of it can write in the doc. > > I also think that it is better avoid 'y' and 'n' (though as you said it would work), but use integers for all cases. > Less confusion for the users. > Konstantin > +1 Also expand "REP" to "REP_COUNT" to make it clear that it's a numeric value. /Bruce