From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Yuanhan Liu <yliu@fridaylinux.org>
Cc: dev@dpdk.org, jfreiman@redhat.com, tiwei.bie@intel.com,
mst@redhat.com, vkaplans@redhat.com, jasowang@redhat.com
Subject: Re: [dpdk-dev] [PATCH 07/21] vhost: add iotlb helper functions
Date: Fri, 8 Sep 2017 10:50:49 +0200 [thread overview]
Message-ID: <3150540a-66ee-b686-7553-a4c988a2f18d@redhat.com> (raw)
In-Reply-To: <20170908083633.GG9736@yliu-home>
On 09/08/2017 10:36 AM, Yuanhan Liu wrote:
> On Fri, Sep 08, 2017 at 10:24:58AM +0200, Maxime Coquelin wrote:
>>
>>
>> On 09/08/2017 10:08 AM, Yuanhan Liu wrote:
>>> On Thu, Aug 31, 2017 at 11:50:09AM +0200, Maxime Coquelin wrote:
>>>> diff --git a/lib/librte_vhost/iotlb.c b/lib/librte_vhost/iotlb.c
>>>> new file mode 100644
>>>> index 000000000..1b739dae5
>>>> --- /dev/null
>>>> +++ b/lib/librte_vhost/iotlb.c
>>>> @@ -0,0 +1,231 @@
>>>> +/*-
>>>> + * BSD LICENSE
>>>> + *
>>>> + * Copyright (c) 2017 Red Hat, Inc.
>>>> + * Copyright (c) 2017 Maxime Coquelin <maxime.coquelin@redhat.com>
>>>
>>> I'm not a lawer, but I have been told many years before, that you don't
>>> have the copyright for the code you write for open source project, the
>>> company you work for does.
>>>
>>> Thus, it's more common to see something like following:
>>> Copyright , ... the commany ...
>>> Author: Some One <...@...>
>>>
>>> However, as you may have noticed, it's not common to put the authorship
>>> in the source files. Though I don't object it.
>>
>> I'm not a lawyer too. At least in other projects, it seems common the
>> author puts his name as copyright owner.
>>
>> I have no issue to change it to only keep Red Hat's one though.
>
> That's up to you. What I said before was JFYI :)
>
>>> [...]
>>>> +#define IOTLB_CACHE_SIZE 1024
>>>> +
>>>> +static void vhost_user_iotlb_cache_remove_all(struct vhost_virtqueue *vq)
>>> ^^^^^^^^^^^^
>>> Note that it's not the DPDK coding style to define a function.
>>
>> Ok, I guess you mean:
>> static void
>> vhost_user_iotlb_cache_remove_all(struct vhost_virtqueue *vq) ?
>
> Yep.
>
>>>> +{
>>>> + struct vhost_iotlb_entry *node, *temp_node;
>>>> +
>>>> + rte_rwlock_write_lock(&vq->iotlb_lock);
>>>> +
>>>> + TAILQ_FOREACH_SAFE(node, &vq->iotlb_list, next, temp_node) {
>>>> + TAILQ_REMOVE(&vq->iotlb_list, node, next);
>>>> + rte_mempool_put(vq->iotlb_pool, node);
>>>> + }
>>>> +
>>>> + rte_rwlock_write_unlock(&vq->iotlb_lock);
>>>> +}
>>>> +
>>>> +void vhost_user_iotlb_cache_insert(struct vhost_virtqueue *vq, uint64_t iova,
>>>> + uint64_t uaddr, uint64_t size, uint8_t perm)
>>>> +{
>>>> + struct vhost_iotlb_entry *node, *new_node;
>>>> + int ret;
>>>> +
>>>> + ret = rte_mempool_get(vq->iotlb_pool, (void **)&new_node);
>>>> + if (ret) {
>>>> + RTE_LOG(ERR, VHOST_CONFIG, "IOTLB pool empty, invalidate cache\n");
>>>
>>> It's a cache, why not considering remove one to get space for new one?
>>
>> It would mean having to track every lookups not to remove hot entries,
>> which would have an impact on performance.
>
> You were removing all caches, how can we do worse than that? Even a
> random evict would be better. Or, more simply, just to remove the
> head or the tail?
I think removing head or tail could cause deadlocks.
For example it needs to translate from 0x0 to 0x2000, with page size
being 0x1000.
If cache is full, when inserting 0x1000-0x1fff, it will remove
0x0-0xfff, so a miss will be sent for 0x0-0xffff and 0x1000-0x1fff will
be remove at insert time, etc...
Note that we really need to size the cache large enough for performance
purpose, so having the cache full could be cause by either buggy or
malicious guest.
> --yliu
>
>> Moreover, the idea is to have the cache large enough, else you could
>> face packet drops due to random cache misses.
>>
>> We might consider to improve it, but I consider it an optimization that
>> could be implemented later if needed.
>>
>>>> + vhost_user_iotlb_cache_remove_all(vq);
>>>> + ret = rte_mempool_get(vq->iotlb_pool, (void **)&new_node);
>>>> + if (ret) {
>>>> + RTE_LOG(ERR, VHOST_CONFIG, "IOTLB pool still empty, failure\n");
>>>> + return;
>>>> + }
>>>> + }
next prev parent reply other threads:[~2017-09-08 8:51 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-31 9:50 [dpdk-dev] [PATCH 00/21] Vhost-user: Implement device IOTLB support Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 01/21] Revert "vhost: workaround MQ fails to startup" Maxime Coquelin
2017-09-07 11:54 ` Yuanhan Liu
2017-09-07 12:59 ` Maxime Coquelin
2017-09-24 10:41 ` Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 02/21] vhost: make error handling consistent in rx path Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 03/21] vhost: protect virtio_net device struct Maxime Coquelin
2017-09-05 4:45 ` Tiwei Bie
2017-09-05 9:24 ` Maxime Coquelin
2017-09-05 10:07 ` Tiwei Bie
2017-09-05 11:00 ` Maxime Coquelin
2017-09-06 1:15 ` Tiwei Bie
2017-09-06 2:59 ` Stephen Hemminger
2017-09-06 7:50 ` Maxime Coquelin
2017-09-06 7:15 ` Maxime Coquelin
2017-09-06 7:30 ` Tiwei Bie
2017-09-06 20:02 ` Maxime Coquelin
2017-09-07 5:08 ` Tiwei Bie
2017-09-07 13:44 ` Yuanhan Liu
2017-09-07 14:01 ` Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 04/21] vhost: prepare send_vhost_message() to slave requests Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 05/21] vhost: add support to slave requests channel Maxime Coquelin
2017-09-05 4:19 ` Tiwei Bie
2017-09-05 8:18 ` Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 06/21] vhost: declare missing IOMMU-related definitions for old kernels Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 07/21] vhost: add iotlb helper functions Maxime Coquelin
2017-09-05 6:02 ` Tiwei Bie
2017-09-05 15:16 ` Maxime Coquelin
2017-09-08 8:08 ` Yuanhan Liu
2017-09-08 8:24 ` Maxime Coquelin
2017-09-08 8:36 ` Yuanhan Liu
2017-09-08 8:50 ` Maxime Coquelin [this message]
2017-09-08 9:21 ` Yuanhan Liu
2017-09-08 9:28 ` Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 08/21] vhost: iotlb: add pending miss request list and helpers Maxime Coquelin
2017-09-05 7:11 ` Tiwei Bie
2017-09-05 15:18 ` Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 09/21] vhost-user: add support to IOTLB miss slave requests Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 10/21] vhost: initialize vrings IOTLB caches Maxime Coquelin
2017-09-04 13:57 ` Remy Horton
2017-09-04 15:45 ` Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 11/21] vhost-user: handle IOTLB update and invalidate requests Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 12/21] vhost: introduce guest IOVA to backend VA helper Maxime Coquelin
2017-09-05 4:14 ` Tiwei Bie
2017-09-05 7:05 ` Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 13/21] vhost: use the guest IOVA to host " Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 14/21] vhost: enable rings at the right time Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 15/21] vhost: don't dereference invalid dev pointer after its reallocation Maxime Coquelin
2017-09-04 13:58 ` Remy Horton
2017-08-31 9:50 ` [dpdk-dev] [PATCH 16/21] vhost: postpone rings addresses translation Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 17/21] vhost-user: translate ring addresses when IOMMU enabled Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 18/21] vhost-user: iommu: postpone device creation until ring are mapped Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 19/21] vhost: iommu: Invalidate vring in case of matching IOTLB invalidate Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 20/21] vhost: enable IOMMU support Maxime Coquelin
2017-08-31 9:50 ` [dpdk-dev] [PATCH 21/21] vhost: iotlb: reduce iotlb read lock usage Maxime Coquelin
2017-09-11 4:18 ` Yuanhan Liu
2017-09-11 7:34 ` Maxime Coquelin
2017-09-11 9:39 ` Yuanhan Liu
2017-09-04 13:58 ` [dpdk-dev] [PATCH 00/21] Vhost-user: Implement device IOTLB support Remy Horton
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