# Distributed data parallel freezes without error message

**URL:** <https://discuss.pytorch.org/t/distributed-data-parallel-freezes-without-error-message/8009>\
**Category:** Uncategorized\
**Created:** [September 28, 2017, 4:46pm UTC](https://discuss.pytorch.org/t/distributed-data-parallel-freezes-without-error-message/8009 "2017-09-28T16:46:57Z")\
**Posts on this page:** 1\
**Showing post:** 28

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**Author:** ![111411](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/111411/32/31674_2.png) [@111411](https://discuss.pytorch.org/u/111411)\
**Post date:** [December 15, 2020, 11:21am UTC](https://discuss.pytorch.org/t/distributed-data-parallel-freezes-without-error-message/8009/28 "2020-12-15T11:21:34Z")

</div>

I found the answer!

modify /etc/default/grub

```auto
#GRUB_CMDLINE_LINUX="" <—— Original commented
GRUB_CMDLINE_LINUX="iommu=soft" <——— Change

```

ref : [https://github.com/pytorch/pytorch/issues/1637#issuecomment-338268158](https://github.com/pytorch/pytorch/issues/1637#issuecomment-338268158)

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