From: Pankaj Gupta <pagupta@redhat.com> To: Jason Wang <jasowang@redhat.com> Cc: mst@redhat.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] vhost: lockless enqueuing Date: Tue, 26 Apr 2016 03:57:10 -0400 (EDT) [thread overview] Message-ID: <19697601.46250110.1461657430875.JavaMail.zimbra@redhat.com> (raw) In-Reply-To: <571F1330.7030504@redhat.com> > > > > On 04/26/2016 02:24 PM, Pankaj Gupta wrote: > > Hi Jason, > > > > Overall patches look good. Just one doubt I have is below: > >> We use spinlock to synchronize the work list now which may cause > >> unnecessary contentions. So this patch switch to use llist to remove > >> this contention. Pktgen tests shows about 5% improvement: > >> > >> Before: > >> ~1300000 pps > >> After: > >> ~1370000 pps > >> > >> Signed-off-by: Jason Wang <jasowang@redhat.com> > >> --- > >> drivers/vhost/vhost.c | 52 > >> +++++++++++++++++++++++++-------------------------- > >> drivers/vhost/vhost.h | 7 ++++--- > >> 2 files changed, 29 insertions(+), 30 deletions(-) > > [...] > > >> - if (work) { > >> + node = llist_del_all(&dev->work_list); > >> + if (!node) > >> + schedule(); > >> + > >> + node = llist_reverse_order(node); > > Can we avoid llist reverse here? > > > > Probably not, this is because: > > - we should process the work exactly the same order as they were queued, > otherwise flush won't work > - llist can only add a node to the head of list. Got it. Thanks, > > Thanks >
WARNING: multiple messages have this Message-ID (diff)
From: Pankaj Gupta <pagupta@redhat.com> To: Jason Wang <jasowang@redhat.com> Cc: netdev@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, mst@redhat.com Subject: Re: [PATCH 2/2] vhost: lockless enqueuing Date: Tue, 26 Apr 2016 03:57:10 -0400 (EDT) [thread overview] Message-ID: <19697601.46250110.1461657430875.JavaMail.zimbra@redhat.com> (raw) In-Reply-To: <571F1330.7030504@redhat.com> > > > > On 04/26/2016 02:24 PM, Pankaj Gupta wrote: > > Hi Jason, > > > > Overall patches look good. Just one doubt I have is below: > >> We use spinlock to synchronize the work list now which may cause > >> unnecessary contentions. So this patch switch to use llist to remove > >> this contention. Pktgen tests shows about 5% improvement: > >> > >> Before: > >> ~1300000 pps > >> After: > >> ~1370000 pps > >> > >> Signed-off-by: Jason Wang <jasowang@redhat.com> > >> --- > >> drivers/vhost/vhost.c | 52 > >> +++++++++++++++++++++++++-------------------------- > >> drivers/vhost/vhost.h | 7 ++++--- > >> 2 files changed, 29 insertions(+), 30 deletions(-) > > [...] > > >> - if (work) { > >> + node = llist_del_all(&dev->work_list); > >> + if (!node) > >> + schedule(); > >> + > >> + node = llist_reverse_order(node); > > Can we avoid llist reverse here? > > > > Probably not, this is because: > > - we should process the work exactly the same order as they were queued, > otherwise flush won't work > - llist can only add a node to the head of list. Got it. Thanks, > > Thanks >
next prev parent reply other threads:[~2016-04-26 7:57 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-04-26 2:14 [PATCH 1/2] vhost: simplify work flushing Jason Wang 2016-04-26 2:14 ` Jason Wang 2016-04-26 2:14 ` [PATCH 2/2] vhost: lockless enqueuing Jason Wang 2016-04-26 6:24 ` Pankaj Gupta 2016-04-26 7:05 ` Jason Wang 2016-04-26 7:05 ` Jason Wang 2016-04-26 7:57 ` Pankaj Gupta [this message] 2016-04-26 7:57 ` Pankaj Gupta 2016-04-26 6:24 ` Pankaj Gupta 2016-04-26 2:14 ` Jason Wang
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