TheNCCL_PROTOvariable defines which protocol NCCL will use. Values accepted¶ Coma-separated list of protocols (not case sensitive) among: LL, LL128, Simple. To specify protocols to exclude (instead of include), start the list with ^. ...
(github issue #379) NVIDIA Collective Communication Library (NCCL) RN-08645-000_v2.9.6 | 10 NCCL Release 2.8.3 ‣ Protocol mismatch causing hangs or crashes when using one GPU per node. (github issue #394) NVIDIA Collective Communication Library (NCCL) RN-08645-000_v2.9.6 | 11 Chapter...
在使用 GPU 服务器安装 GluonTS 做时间序列预测有关的项目时,报错如下(吐槽,用 MXNet 的时候,经常遇到报错emmm):
static ncclResult_t computeColl(struct ncclInfo* info /* input */, struct ncclColl* coll, struct ncclProxyArgs* proxyArgs /* output */) {...int stepSize = info->comm->buffSizes[info->protocol]/NCCL_STEPS;int chunkSteps = (info->protocol == NCCL_PROTO_SIMPLE && info->algorithm ==...
The overhead bytes are protocol overhead for using nvlink, and not specific to nccl. It’s hard to say why the ratio is what it is. Perhaps the algorithm is only sending small amounts of data per transmission. You may need to talk with the nccl team or dig deeper into the perf ana...
The overhead bytes are protocol overhead for using nvlink, and not specific to nccl. It’s hard to say why the ratio is what it is. Perhaps the algorithm is only sending small amounts of data per transmission. You may need to talk with the nccl team or dig deeper into the perf ana...
[0] NCCL INFO Protocol | LL | LL128 | Simple | LL | LL128 | Simple | LL | LL128 | Simple | nathan-h100-1:14492:14605 [0] NCCL INFO Max NThreads | 0 | 0 | 640 | 0 | 0 | 640 | 0 | 0 | 640 | nathan-h100-1:14492:14605 [0] NCCL INFO Broadcast | 0.0/ 0.0 | 0.0...
sjeaugey commentedon Jan 3, 2023 sjeaugey It could be normal... depends on the number of GPUs (number of nodes, number of GPUs per node), and the size of the operation. The best is usually to run the NCCL perf tests to see what performance you get from Tree and Ring, then we ...
NCCL通信协议一共有Simple, LL, LL128,本篇博客只关注后两种通信协议。 L(ow)L(atency)协议 以往NCCL为了保证同步,会引入 memory fence,这就导致延迟比较大。 而在小数据量下,往往打不满传输带宽,此时优化点在于同步带来的延迟。 LL协议依赖前提是 CUDA 的memory 8Bytes大小的操作是atomic的,因此通信时会将数...
协议:数据构建的协议影响速度,可选的protocol主要是三种,低延时/128B低延时/常规 对应参数:LL/LL128/'Simple。 算法带宽的计算过程:取算法基数值 busBw= ncclTopoGraph->bwIntra ,经过NCCL_ALGO/NCCL_PROTO/NCCL_TOPO等场景修正(即乘以一定的比例系数)后,把结果存储在comm中: 参数含义:coll: 集群通信操作;a:...