diff --git a/doc/PERFORMANCE.md b/doc/PERFORMANCE.md
index 21fef60..942f054 100644
--- a/doc/PERFORMANCE.md
+++ b/doc/PERFORMANCE.md
@@ -140,5 +140,6 @@ To obtain a bus bandwidth which should be independent of the number of ranks _n_
 * AllGather : (_n_-1)/_n_
 * Broadcast : 1
 * Reduce : 1
+* AlltoAll: (_n_-1)/_n_
 
 The bus bandwidth should reflect the speed of the hardware bottleneck : NVLink, PCI, QPI, or network.