put split memory block in the front of memory block set when stream and size equal.

[Shan19900305]

Using split memory block first and will reduce memory fragment.

[pytorch-bot]

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[eqy]

Cool! do you have a small script demoing the effect of this change on an example workload?

[Shan19900305]

Cool! do you have a small script demoing the effect of this change on an example workload?

Thx, Is there a memory fragmentation test case in the community?