From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: "Van Haaren, Harry" <harry.van.haaren@intel.com>,
"Ye, Xiaolong" <xiaolong.ye@intel.com>,
Itsuro Oda <oda@valinux.co.jp>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
"Wang, Zhihong" <zhihong.wang@intel.com>,
"stable@dpdk.org" <stable@dpdk.org>
Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH] vhost: make iotlb cache name unique among multi processes
Date: Tue, 10 Mar 2020 13:58:13 +0100 [thread overview]
Message-ID: <bab413b0-bad7-1011-4669-8b2e8ad55896@redhat.com> (raw)
In-Reply-To: <MWHPR1101MB215772487292E1D005542FFAD7FF0@MWHPR1101MB2157.namprd11.prod.outlook.com>
On 3/10/20 1:44 PM, Van Haaren, Harry wrote:
>> -----Original Message-----
>> From: dev <dev-bounces@dpdk.org> On Behalf Of Ye Xiaolong
>> Sent: Tuesday, March 10, 2020 11:32 AM
>> To: Itsuro Oda <oda@valinux.co.jp>
>> Cc: dev@dpdk.org; maxime.coquelin@redhat.com; Wang, Zhihong
>> <zhihong.wang@intel.com>; stable@dpdk.org
>> Subject: Re: [dpdk-dev] [PATCH] vhost: make iotlb cache name unique among
>> multi processes
>>
>> On 03/10, Itsuro Oda wrote:
>>> Currently, iotlb cache name is comprised of vid and virtqueue
>>> index. For example, "iotlb_cache_0_0". Because vid is assigned
>>> per process, iotlb cache name is not unique among multi processes.
>>> For example a secondary process uses a vhost
>>> (ex. eth_vhost0,iface=/tmp/sock0) and another secondary process
>>> uses a vhost (ex. eth_vhost1,iface=/tmp/sock1), iotlb cache
>>> name of both vhost ("iotlb_cache_0_0") are same and as a result
>>> iotlb cache is broken.
>>>
>>> This patch makes iotlb cache name unique among milti processes
>>> by using the interface name not vid to comprise iotlb cache name.
>>> Since the length of interface name is variable, this patch uses
>>> hash value calculated by the interface name.
>>>
>>> Fixes: d012d1f293f4 (vhost: add IOTLB helper functions)
>>> Cc: stable@dpdk.org
>>>
>>> Signed-off-by: Itsuro Oda <oda@valinux.co.jp>
>>> ---
>>> lib/librte_vhost/iotlb.c | 8 ++++++--
>>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/lib/librte_vhost/iotlb.c b/lib/librte_vhost/iotlb.c
>>> index bc1758528..0992c145b 100644
>>> --- a/lib/librte_vhost/iotlb.c
>>> +++ b/lib/librte_vhost/iotlb.c
>>> @@ -6,6 +6,7 @@
>>> #include <numaif.h>
>>> #endif
>>>
>>> +#include <rte_jhash.h>
>>> #include <rte_tailq.h>
>>>
>>> #include "iotlb.h"
>>> @@ -288,6 +289,7 @@ vhost_user_iotlb_init(struct virtio_net *dev, int
>> vq_index)
>>> char pool_name[RTE_MEMPOOL_NAMESIZE];
>>> struct vhost_virtqueue *vq = dev->virtqueue[vq_index];
>>> int socket = 0;
>>> + uint32_t val;
>>>
>>> if (vq->iotlb_pool) {
>>> /*
>>> @@ -308,8 +310,10 @@ vhost_user_iotlb_init(struct virtio_net *dev, int
>> vq_index)
>>> TAILQ_INIT(&vq->iotlb_list);
>>> TAILQ_INIT(&vq->iotlb_pending_list);
>>>
>>> - snprintf(pool_name, sizeof(pool_name), "iotlb_cache_%d_%d",
>>> - dev->vid, vq_index);
>>> + val = rte_jhash(dev->ifname, strlen(dev->ifname), 0);
>>> + snprintf(pool_name, sizeof(pool_name), "iotlb_cache_%08x_%d",
>>> + val, vq_index);
>>> + VHOST_LOG_CONFIG(DEBUG, "IOTLB cache name: %s\n", pool_name);
>
> Although very unlikely, what would happen if there is a hash-collision?
>
> For example imagine two different names hash to the same "val", from
> my understanding they will now use the same IOTLB but should not share one.
>
> <snip>
>
+1.
Instead of a hash, maybe use the process ID:
snprintf(pool_name, sizeof(pool_name), "iotlb_cache_%u_%d_%d",
pid, dev->vid, vq_index);
next prev parent reply other threads:[~2020-03-10 12:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-10 5:00 [dpdk-stable] " Itsuro Oda
2020-03-10 11:32 ` Ye Xiaolong
2020-03-10 12:44 ` [dpdk-stable] [dpdk-dev] " Van Haaren, Harry
2020-03-10 12:58 ` Maxime Coquelin [this message]
2020-03-11 0:24 ` [dpdk-stable] [PATCH v2] " Itsuro Oda
2020-03-11 23:19 ` [dpdk-stable] [PATCH v3] " Itsuro Oda
2020-04-09 14:25 ` Maxime Coquelin
2020-04-10 14:45 ` Maxime Coquelin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=bab413b0-bad7-1011-4669-8b2e8ad55896@redhat.com \
--to=maxime.coquelin@redhat.com \
--cc=dev@dpdk.org \
--cc=harry.van.haaren@intel.com \
--cc=oda@valinux.co.jp \
--cc=stable@dpdk.org \
--cc=xiaolong.ye@intel.com \
--cc=zhihong.wang@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).