linux-kernel - Re: [PATCH rdma-next 00/10] Enable relaxed ordering for ULPs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 6 Apr 2021 08:09:43 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     Honggang LI <honli@...hat.com>
Cc:     Doug Ledford <dledford@...hat.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Adit Ranadive <aditr@...are.com>,
        Anna Schumaker <anna.schumaker@...app.com>,
        Ariel Elior <aelior@...vell.com>,
        Avihai Horon <avihaih@...dia.com>,
        Bart Van Assche <bvanassche@....org>,
        Bernard Metzler <bmt@...ich.ibm.com>,
        Christoph Hellwig <hch@....de>,
        Chuck Lever <chuck.lever@...cle.com>,
        "David S. Miller" <davem@...emloft.net>,
        Dennis Dalessandro <dennis.dalessandro@...nelisnetworks.com>,
        Devesh Sharma <devesh.sharma@...adcom.com>,
        Faisal Latif <faisal.latif@...el.com>,
        Jack Wang <jinpu.wang@...os.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "J. Bruce Fields" <bfields@...ldses.org>,
        Jens Axboe <axboe@...com>,
        Karsten Graul <kgraul@...ux.ibm.com>,
        Keith Busch <kbusch@...nel.org>, Lijun Ou <oulijun@...wei.com>,
        linux-cifs@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-nfs@...r.kernel.org, linux-nvme@...ts.infradead.org,
        linux-rdma@...r.kernel.org, linux-s390@...r.kernel.org,
        Max Gurtovoy <maxg@...lanox.com>,
        Max Gurtovoy <mgurtovoy@...dia.com>,
        "Md. Haris Iqbal" <haris.iqbal@...os.com>,
        Michael Guralnik <michaelgur@...dia.com>,
        Michal Kalderon <mkalderon@...vell.com>,
        Mike Marciniszyn <mike.marciniszyn@...nelisnetworks.com>,
        Naresh Kumar PBS <nareshkumar.pbs@...adcom.com>,
        netdev@...r.kernel.org, Potnuri Bharat Teja <bharat@...lsio.com>,
        rds-devel@....oracle.com, Sagi Grimberg <sagi@...mberg.me>,
        samba-technical@...ts.samba.org,
        Santosh Shilimkar <santosh.shilimkar@...cle.com>,
        Selvin Xavier <selvin.xavier@...adcom.com>,
        Shiraz Saleem <shiraz.saleem@...el.com>,
        Somnath Kotur <somnath.kotur@...adcom.com>,
        Sriharsha Basavapatna <sriharsha.basavapatna@...adcom.com>,
        Steve French <sfrench@...ba.org>,
        Trond Myklebust <trond.myklebust@...merspace.com>,
        VMware PV-Drivers <pv-drivers@...are.com>,
        Weihang Li <liweihang@...wei.com>,
        Yishai Hadas <yishaih@...dia.com>,
        Zhu Yanjun <zyjzyj2000@...il.com>
Subject: Re: [PATCH rdma-next 00/10] Enable relaxed ordering for ULPs

On Tue, Apr 06, 2021 at 10:37:38AM +0800, Honggang LI wrote:
> On Mon, Apr 05, 2021 at 08:23:54AM +0300, Leon Romanovsky wrote:
> > From: Leon Romanovsky <leonro@...dia.com>
> > 
> > From Avihai,
> > 
> > Relaxed Ordering is a PCIe mechanism that relaxes the strict ordering
> > imposed on PCI transactions, and thus, can improve performance.
> > 
> > Until now, relaxed ordering could be set only by user space applications
> > for user MRs. The following patch series enables relaxed ordering for the
> > kernel ULPs as well. Relaxed ordering is an optional capability, and as
> > such, it is ignored by vendors that don't support it.
> > 
> > The following test results show the performance improvement achieved
> 
> Did you test this patchset with CPU does not support relaxed ordering?

I don't think so, the CPUs that don't support RO are Intel's fourth/fifth-generation
and they are not interesting from performance point of view.

> 
> We observed significantly performance degradation when run perftest with
> relaxed ordering enabled over old CPU.
> 
> https://github.com/linux-rdma/perftest/issues/116

The perftest is slightly different, but you pointed to the valid point.
We forgot to call pcie_relaxed_ordering_enabled() before setting RO bit
and arguably this was needed to be done in perftest too.

Thanks

> 
> thanks
>