benchmarks of O_STREAMING in 2.5

From: Robert Love (
Date: Wed Oct 16 2002 - 21:53:20 EST

I gave the O_STREAMING in Andrew's 2.5-mm tree the treatment..

Short summary: It works.

The streaming read test in the following benchmarks is simply a read()
in 64KB byte chunks of an 800MB file.

First test. Show the cache effects are indeed as we intend and the
overhead is negligible. Here, mem=2G.

        O_STREAMING? Wall time Cache Delta
        Yes 21.827s 0
        No 21.734s +800MB

Second test. Same deal, but mem=8M. There was slight swapping, so I
suspect the reduced VM pressure is why the O_STREAMING run is faster.

        O_STREAMING? Wall time Cache Delta
        Yes 22.303s 0
        No 28.812s +1MB

Third and final test. Kernel compile (make -j2) with a couple streaming
reads in the background. Again, mem=2G. This shows that actually
saving the pagecache from the horrid waste is useful.

        O_STREAMING Wall time to complete Kernel compile
        Yes 5m30.494s
        No 4m59.661s

So, uh, Andrew's 2.5 code works ;-)

Someone buy me a dual Xeon,

        Robert Love

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

This archive was generated by hypermail 2b29 : Wed Oct 23 2002 - 22:00:31 EST