From: "Michael S. Tsirkin" <mst-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: Or Gerlitz <or.gerlitz-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Roland Dreier <roland-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
Yan Burman <yanb-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: decent performance drop for SCSI LLD / SAN initiator when iommu is turned on
Date: Thu, 2 May 2013 04:56:03 +0300 [thread overview]
Message-ID: <20130502015603.GC26105@redhat.com> (raw)
In-Reply-To: <CAJZOPZJ8eF-Q+WFzA-_vvzkpSb41PQjKFo27_Wi3McUccOqs9A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
On Thu, May 02, 2013 at 02:11:15AM +0300, Or Gerlitz wrote:
> Hi Roland, IOMMU folks,
>
> So we've noted that when configuring the kernel && booting with intel
> iommu set to on on a physical node (non VM, and without enabling SRIOV
> by the HW device driver) raw performance of the iSER (iSCSI RDMA) SAN
> initiator is reduced notably, e.g in the testbed we looked today we
> had ~260K 1KB random IOPS and 5.5GBs BW for 128KB IOs with iommu
> turned off for single LUN, and ~150K IOPS and 4GBs BW with iommu
> turned on. No change on the target node between runs.
That's why we have iommu=pt.
See definition of iommu_pass_through in arch/x86/kernel/pci-dma.c.
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next prev parent reply other threads:[~2013-05-02 1:56 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-01 23:11 decent performance drop for SCSI LLD / SAN initiator when iommu is turned on Or Gerlitz
[not found] ` <CAJZOPZJ8eF-Q+WFzA-_vvzkpSb41PQjKFo27_Wi3McUccOqs9A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-05-02 0:13 ` Roland Dreier
2013-05-02 1:56 ` Michael S. Tsirkin [this message]
[not found] ` <20130502015603.GC26105-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2013-05-02 14:13 ` Yan Burman
[not found] ` <0EE9A1CDC8D6434DB00095CD7DB873462CF9D73E-fViJhHBwANKuSA5JZHE7gA@public.gmane.org>
2013-05-03 19:40 ` Don Dutile
[not found] ` <518412AC.3070507-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2013-05-05 14:06 ` Yan Burman
2013-05-06 21:39 ` Or Gerlitz
[not found] ` <CAJZOPZLWgXNCEpZjzuizVGPEVPg1G+cHh373ZCoumMx9eAabvQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-05-06 22:35 ` Alexander Duyck
[not found] ` <5188304E.9050603-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
2013-05-07 12:12 ` Or Gerlitz
2013-05-07 12:22 ` Michael S. Tsirkin
[not found] ` <20130507122235.GA21361-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2013-05-07 14:50 ` Or Gerlitz
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