[dpdk-dev] [PATCH] net/virtio-user: fix hugepage files enumeration

Maxime Coquelin maxime.coquelin at redhat.com
Fri May 4 09:40:03 CEST 2018


Hi Anatoly,

On 04/27/2018 11:31 AM, Burakov, Anatoly wrote:
> On 26-Apr-18 4:34 PM, Jianfeng Tan wrote:
>> After the commit 2a04139f66b4 ("eal: add single file segments option"),
>> one hugepage file could contain multiple hugepages which are further
>> mapped to different memory regions.
>>
>> Original enumeration implementation cannot handle this situation.
>>
>> This patch filters out the duplicated files; and adjust the size after
>> the enumeration.
>>
>> Fixes: 6a84c37e3975 ("net/virtio-user: add vhost-user adapter layer")
>>
>> Signed-off-by: Jianfeng Tan <jianfeng.tan at intel.com>
>> ---
>>   .../howto/virtio_user_for_container_networking.rst |  3 ++-
>>   drivers/net/virtio/virtio_user/vhost_user.c        | 28 
>> ++++++++++++++++++++--
>>   2 files changed, 28 insertions(+), 3 deletions(-)
>>
>> diff --git a/doc/guides/howto/virtio_user_for_container_networking.rst 
>> b/doc/guides/howto/virtio_user_for_container_networking.rst
>> index aa68b53..476ce3a 100644
>> --- a/doc/guides/howto/virtio_user_for_container_networking.rst
>> +++ b/doc/guides/howto/virtio_user_for_container_networking.rst
>> @@ -109,7 +109,8 @@ We have below limitations in this solution:
>>    * Cannot work with --no-huge option. Currently, DPDK uses anonymous 
>> mapping
>>      under this option which cannot be reopened to share with vhost 
>> backend.
>>    * Cannot work when there are more than VHOST_MEMORY_MAX_NREGIONS(8) 
>> hugepages.
>> -   In another word, do not use 2MB hugepage so far.
>> +   If you have more regions (especially when 2MB hugepages are used), 
>> the option,
>> +   --single-file-segments, can help to reduce the number of shared 
>> files.
>>    * Applications should not use file name like HUGEFILE_FMT 
>> ("%smap_%d"). That
>>      will bring confusion when sharing hugepage files with backend by 
>> name.
>>    * Root privilege is a must. DPDK resolves physical addresses of 
>> hugepages
>> diff --git a/drivers/net/virtio/virtio_user/vhost_user.c 
>> b/drivers/net/virtio/virtio_user/vhost_user.c
>> index a6df97a..01201c9 100644
>> --- a/drivers/net/virtio/virtio_user/vhost_user.c
>> +++ b/drivers/net/virtio/virtio_user/vhost_user.c
>> @@ -138,12 +138,13 @@ struct hugepage_file_info {
>>   static int
>>   get_hugepage_file_info(struct hugepage_file_info huges[], int max)
>>   {
>> -    int idx;
>> +    int idx, k, exist;
>>       FILE *f;
>>       char buf[BUFSIZ], *tmp, *tail;
>>       char *str_underline, *str_start;
>>       int huge_index;
>>       uint64_t v_start, v_end;
>> +    struct stat stats;
>>       f = fopen("/proc/self/maps", "r");
>>       if (!f) {
>> @@ -183,16 +184,39 @@ get_hugepage_file_info(struct hugepage_file_info 
>> huges[], int max)
>>           if (sscanf(str_start, "map_%d", &huge_index) != 1)
>>               continue;
>> +        /* skip duplicated file which is mapped to different regions */
>> +        for (k = 0, exist = -1; k < idx; ++k) {
>> +            if (!strcmp(huges[k].path, tmp)) {
>> +                exist = k;
>> +                break;
>> +            }
>> +        }
>> +        if (exist >= 0)
>> +            continue;
>> +
>>           if (idx >= max) {
>>               PMD_DRV_LOG(ERR, "Exceed maximum of %d", max);
>>               goto error;
>>           }
>> +
>>           huges[idx].addr = v_start;
>> -        huges[idx].size = v_end - v_start;
>> +        huges[idx].size = v_end - v_start; /* To be corrected later */
>>           snprintf(huges[idx].path, PATH_MAX, "%s", tmp);
>>           idx++;
>>       }
>> +    /* correct the size for files who have many regions */
>> +    for (k = 0; k < idx; ++k) {
>> +        if (stat(huges[k].path, &stats) < 0) {
>> +            PMD_DRV_LOG(ERR, "Failed to stat %s, %s\n",
>> +                    huges[k].path, strerror(errno));
>> +            continue;
>> +        }
>> +        huges[k].size = stats.st_size;
>> +        PMD_DRV_LOG(INFO, "file %s, size %"PRIx64"\n",
>> +                huges[k].path, huges[k].size);
>> +    }
>> +
>>       fclose(f);
>>       return idx;
>>
> 
> That sounds like potentially a lot of strcmp()'s (quadratic?). Can't it 
> be sped up somehow? Maybe use rte_hash for storing this data?
> 

This patch is required to have virtio-user to work with 2MB pages.
While it may be improved later, I think we should pick it for v18.05.
Is it fine for you?

Thanks,
Maxime


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