> -----Original Message----- > From: Maxime Coquelin [mailto:maxime.coque...@redhat.com] > Sent: Friday, October 11, 2019 10:22 PM > To: Liu, Yong <yong....@intel.com>; Bie, Tiwei <tiwei....@intel.com>; Wang, > Zhihong <zhihong.w...@intel.com>; step...@networkplumber.org; > gavin...@arm.com > Cc: dev@dpdk.org > Subject: Re: [PATCH v4 03/14] vhost: add batch enqueue function for packed > ring > > > > On 10/9/19 3:38 PM, Marvin Liu wrote: > > Batch enqueue function will first check whether descriptors are cache > > aligned. It will also check prerequisites in the beginning. Batch > > enqueue function not support chained mbufs, single packet enqueue > > function will handle it. > > > > Signed-off-by: Marvin Liu <yong....@intel.com> > > > > Thinking again about this patch and series in general... > > So this series improves performance by 40% in cases where: > - descriptors are cache aligned > - single mbuf > > But my understanding is that it will cause performance regression for > the other cases, which may not be that uncommon, no? > > Do you have some number about the performance impact on these other > cases? >
Hi Maxime, Check prerequisites of batch handling is pretty simple and fast. It almost has no performance impact on uncommon case. Chained packets can slightly benefit from cache related optimization. As shown in below table, all cases I run can benefit from vhost optimization. From our experimental, more performance gain can be seen if more packets handled by batch. +---------------------------------------------------+ | | 19.08 | + opt | |-----------------------------------|-------|-------| | 1518B PvP | 2.63M | 2.98M | |-----------------------------------|-------|-------| | 64B loopback | 7.81M | 12.0M | |-----------------------------------|-------|-------| | 1518B loopback | 3.59M | 4.69M | |-----------------------------------|-------|-------| | 16K chained loopback | 297K | 306K | |-----------------------------------|-------|-------| | 50% 256B + 50% 16K | 296K | 309K | |-----------------------------------|-------|-------| | pktgen_sample03_burst_single_flow | 6.03M | 6.39M | +---------------------------------------------------+ Regards, Marvin > Thanks, > Maxime
