Bug 1401436
| Summary: | lockless en-queuing for vhost | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 7 | Reporter: | jason wang <jasowang> |
| Component: | kernel | Assignee: | Wei <wexu> |
| kernel sub component: | Virtualization | QA Contact: | Quan Wenli <wquan> |
| Status: | CLOSED ERRATA | Docs Contact: | Jiri Herrmann <jherrman> |
| Severity: | unspecified | ||
| Priority: | high | CC: | ailan, chayang, juzhang, michen, mtessun, pezhang, weliao, wexu, wquan, yama |
| Version: | 7.4 | Keywords: | FutureFeature |
| Target Milestone: | rc | ||
| Target Release: | 7.4 | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
| Whiteboard: | |||
| Fixed In Version: | kernel-3.10.0-628.el7 | Doc Type: | If docs needed, set a value |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2017-08-02 04:53:19 UTC | Type: | Bug |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
| Bug Depends On: | |||
| Bug Blocks: | 1395265 | ||
Downstream test result on my laptop: Before: tap2 RX 1564831 pkts/s RX Dropped: 0 pkts/s tap1 TX 2180650 pkts/s TX Dropped: 1677842 pkts/s After: tap2 RX 1582509 pkts/s RX Dropped: 0 pkts/s tap1 TX 2232357 pkts/s TX Dropped: 1702915 pkts/s Patch(es) committed on kernel repository and an interim kernel build is undergoing testing Patch(es) available on kernel-3.10.0-628.el7 Hi Jiri, I just had a quick look at previous release note for RHEL7.0, since this bz is a performance improvement which differs from a new feature, it is good to keep it out of the release note AFAICT. Hi Wenli, Could you help to do performance test? Thanks, Xiyue (In reply to xiywang from comment #9) > Hi Wenli, > > Could you help to do performance test? > > Thanks, > Xiyue Pps performance indeed improve with kernel-3.10.0-628, so set it to verified. Steps: 1.run pktgen.sh on tap0 device. 2.gather pps result on guest. host kernel pkts/s ------------------+--------------+ kernel-3.10.0-627 1130227 ------------------+--------------+ kernel-3.10.0-628 1166072 ------------------+--------------+ Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHSA-2017:1842 |
Description of problem: The following patches needs to be backported: commit 04b96e5528ca97199b429810fe963185a67dd40e Author: Jason Wang <jasowang> Date: Mon Apr 25 22:14:33 2016 -0400 vhost: lockless enqueuing 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> Reviewed-by: Michael S. Tsirkin <mst> Signed-off-by: Michael S. Tsirkin <mst> commit 7235acdb1144460d9f520f0d931f3cbb79eb244c Author: Jason Wang <jasowang> Date: Mon Apr 25 22:14:32 2016 -0400 vhost: simplify work flushing We used to implement the work flushing through tracking queued seq, done seq, and the number of flushing. This patch simplify this by just implement work flushing through another kind of vhost work with completion. This will be used by lockless enqueuing patch. Signed-off-by: Jason Wang <jasowang> Reviewed-by: Michael S. Tsirkin <mst> Signed-off-by: Michael S. Tsirkin <mst> Testing: - compare the pktgen/netperf performance Version-Release number of selected component (if applicable): How reproducible: Steps to Reproduce: 1. 2. 3. Actual results: Expected results: Additional info: