From: "Charles (Chas) Williams" <ciwillia@brocade.com>
To: Jan Blunck <jblunck@infradead.org>
Cc: dev <dev@dpdk.org>, <yongwang@vmware.com>
Subject: Re: [dpdk-dev] [PATCH] net/vmxnet3: fix queue size changes
Date: Wed, 15 Mar 2017 08:34:20 -0400 [thread overview]
Message-ID: <a7aaab12-1bb9-362c-77a2-1de9f38711e2@brocade.com> (raw)
In-Reply-To: <CALe+Z02y_1BDJYO7Hxz+FmC1Y+_WXcEYKbVWOwCKcJ2c9dFW+Q@mail.gmail.com>
On 03/15/2017 06:05 AM, Jan Blunck wrote:
> On Wed, Mar 15, 2017 at 10:45 AM, Charles (Chas) Williams
> <ciwillia@brocade.com> wrote:
>>
>>
>> On 03/15/2017 04:18 AM, Jan Blunck wrote:
>>>
>>> On Tue, Mar 14, 2017 at 5:38 PM, Charles (Chas) Williams
>>> <ciwillia@brocade.com> wrote:
>>>>
>>>>
>>>>
>>>> On 03/14/2017 12:11 PM, Jan Blunck wrote:
>>>>>
>>>>>
>>>>> On Mon, Mar 13, 2017 at 11:41 PM, Charles (Chas) Williams
>>>>> <ciwillia@brocade.com> wrote:
>>>>>>
>>>>>>
>>>>>> If the user reconfigures the queues size, then the previosly allocated
>>>>>> memzone may potentially be too small. Instead, always free the old
>>>>>> memzone and allocate a new one.
>>>>>>
>>>>>> Fixes: dfaff37fc46d ("vmxnet3: import new vmxnet3 poll mode driver
>>>>>> implementation")
>>>>>>
>>>>>> Signed-off-by: Chas Williams <ciwillia@brocade.com>
>>>>>> ---
>>>>>> drivers/net/vmxnet3/vmxnet3_rxtx.c | 6 +++---
>>>>>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/net/vmxnet3/vmxnet3_rxtx.c
>>>>>> b/drivers/net/vmxnet3/vmxnet3_rxtx.c
>>>>>> index 6649c3f..104e040 100644
>>>>>> --- a/drivers/net/vmxnet3/vmxnet3_rxtx.c
>>>>>> +++ b/drivers/net/vmxnet3/vmxnet3_rxtx.c
>>>>>> @@ -893,8 +893,8 @@ vmxnet3_recv_pkts(void *rx_queue, struct rte_mbuf
>>>>>> **rx_pkts, uint16_t nb_pkts)
>>>>>>
>>>>>> /*
>>>>>> * Create memzone for device rings. malloc can't be used as the
>>>>>> physical
>>>>>> address is
>>>>>> - * needed. If the memzone is already created, then this function
>>>>>> returns
>>>>>> a ptr
>>>>>> - * to the old one.
>>>>>> + * needed. If the memzone already exists, we free it since it may have
>>>>>> been created
>>>>>> + * with a different size.
>>>>>> */
>>>>>> static const struct rte_memzone *
>>>>>> ring_dma_zone_reserve(struct rte_eth_dev *dev, const char *ring_name,
>>>>>> @@ -909,7 +909,7 @@ ring_dma_zone_reserve(struct rte_eth_dev *dev,
>>>>>> const
>>>>>> char *ring_name,
>>>>>>
>>>>>> mz = rte_memzone_lookup(z_name);
>>>>>> if (mz)
>>>>>> - return mz;
>>>>>> + rte_memzone_free(mz);
>>>>>>
>>>>>> return rte_memzone_reserve_aligned(z_name, ring_size,
>>>>>> socket_id, 0,
>>>>>> VMXNET3_RING_BA_ALIGN);
>>>>>
>>>>>
>>>>>
>>>>> Chas,
>>>>>
>>>>> Thanks for hunting this one down. Wouldn't the rte_memzone_free()
>>>>> better fit into vmxnet3_cmd_ring_release() ?
>>>>
>>>>
>>>>
>>>> I don't care which way it goes. I just did what is basically done in
>>>> gpa_zone_reserve() to match the "style". Tracking the current ring size
>>>> and avoiding reallocating a potentially large chunk of memory seems like
>>>> a better idea.
>>>>
>>>>> Also the ring_dma_zone_reserve() could get replaced by
>>>>> rte_eth_dma_zone_reserve() (see also
>>>>
>>>>
>>>>
>>>> Yes, it probably should get changed to that along with tracking the size.
>>>
>>>
>>> Why don't we always allocate VMXNET3_RX_RING_MAX_SIZE entries? That
>>> way we don't need to reallocate on a later queue setup change?
>>
>>
>> That's using more memory than it needs to use. It might break someone's
>> application
>> that already runs in some tightly constrained machine. Failing to shrink
>> the memzone
>> isn't likely to break anything since they have (apparently) already dealt
>> with having
>> less memory available before switching to a smaller queue size.
>>
>> Still, it can be a matter for another day.
>>
>
> Other drivers (ixgbe, e1000, ...) always allocate based on the max
> ring size too. Since the VMXNET3_RX_RING_MAX_SIZE is 4096 I don't
> think it is a huge waste of memory.
I changed my mind. Our typical application only uses a queue length of
512 for the TX side which would mean we don't use more than half of the
allocated elements. It's easy enough to just allocate what we need and
release in the queue releases as you suggested earlier.
next prev parent reply other threads:[~2017-03-15 12:34 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-13 22:41 Charles (Chas) Williams
2017-03-14 16:11 ` Jan Blunck
2017-03-14 16:38 ` Charles (Chas) Williams
2017-03-15 8:18 ` Jan Blunck
2017-03-15 9:45 ` Charles (Chas) Williams
2017-03-15 10:05 ` Jan Blunck
2017-03-15 10:06 ` Charles (Chas) Williams
2017-03-15 12:34 ` Charles (Chas) Williams [this message]
2017-03-15 12:35 ` Charles (Chas) Williams
2017-03-15 17:57 ` Yong Wang
2017-03-15 18:30 ` Shrikrishna Khare
2017-03-15 18:19 ` Jan Blunck
2017-03-16 11:38 ` Ferruh Yigit
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