Update description2.md

description2.md

@@ -1,5 +1,7 @@
 ## Building a pipeline
 
+Most of existing pipeline schedules can be explained under the following 4 step framework. In the example, we illustrate the construction of 1F1B and Eager 1F1B.
+
 ### Building Block
 It starts by laying out the passes for a single microbatch, which we call a building
 block. For example, the building block of 1F1B schedule is made of a sequence of forward passes
@@ -7,12 +9,14 @@ followed by backward passes in the reverse order.
 
 ### Repeating
 More microbatches are then introduced. The building blocks are repeated and woven
-together to form a pipeline. Notably, legit building blocks are required to repeat without a collision, namely, the
+together to form a pipeline. In the figure below, the repeating building blocks are shown in different shades of grey. 
+Notably, legit building blocks are required to repeat without a collision, namely, the
 passes from two building blocks should not overlap with each other.
 
 ### Squeezing
 Depending on the building block, there may be redundant bubbles in the pipeline, which
-can be simply removed by squeezing without changing the order of the passes.
+can be simply removed by squeezing without changing the order of the passes. For example,
+Eager 1F1B shows a case where squeezing produces more efficient pipeline.
 
 ### Reordering (optional)
 We can reorder the passes in the warm-up and cool-down phase to further
@@ -20,6 +24,10 @@ improve the computation throughput. Intuitively, the peak of memory happens in t
 the pipeline, while in the warm-up and cool-down phases the RAM is under utilized, leaving some
 space for improving the computation throughput without changing peak memory.
 
+| 1F1B | Eager 1F1B |
+|-|-|
+| <img src="https://cdn-uploads.huggingface.co/production/uploads/646968e05d7015663950e95b/olufjIyulR25CvAY6V2Hi.jpeg"/> | <img src="https://cdn-uploads.huggingface.co/production/uploads/646968e05d7015663950e95b/MbxeLnxyCGXNa6HVTt3sx.jpeg"/> |
+
 ## Alternative schedules
 
 By utilizing the building block, we can search for different types of schedules depending on the need. We illustrate few of them here below: