Re: [PATCH 3/6] writeback: sync expired inodes first in backgroundwriteback

[Wu Fengguang]

> wfg /tmp% g cpu log-* | g dd
> log-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.26s system 9% cpu 13.658 total
> log-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.26s system 9% cpu 12.961 total
> log-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.26s system 9% cpu 13.420 total
> log-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.30s system 9% cpu 13.103 total
> log-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.31s system 9% cpu 13.650 total
> log-no-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.25s system 8% cpu 15.258 total
> log-no-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.26s system 8% cpu 14.255 total
> log-no-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.26s system 8% cpu 14.443 total
> log-no-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.25s system 8% cpu 14.051 total
> log-no-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.27s system 8% cpu 14.648 total
> 
> wfg /tmp% g cpu log-* | g tar
> log-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.49s user 3.99s system 60% cpu 27.285 total
> log-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.78s user 4.40s system 65% cpu 26.125 total
> log-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.50s user 4.56s system 64% cpu 26.265 total
> log-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.50s user 4.18s system 62% cpu 26.766 total
> log-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.60s user 4.03s system 60% cpu 27.463 total
> log-no-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.42s user 4.17s system 57% cpu 28.688 total
> log-no-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.67s user 4.04s system 58% cpu 28.738 total
> log-no-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.53s user 4.50s system 58% cpu 29.287 total
> log-no-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.38s user 4.28s system 57% cpu 28.861 total
> log-no-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.44s user 4.19s system 56% cpu 29.443 total

Jan, here are the ext4 numbers. It's also doing better now. And I find
the behaviors and hence dd vs. tar numbers are pretty different from XFS.

- XFS like redirtying the inode after writing pages while ext4 not

- ext4 enforces large 128MB write chunk size, while XFS uses the
  adaptive 24-28MB chunk size (close to half disk bandwidth)

log-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.34s user 3.46s system 93% cpu 16.848 total
log-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.59s user 3.30s system 95% cpu 16.655 total
log-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.45s user 3.54s system 94% cpu 16.881 total
log-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.62s user 3.38s system 93% cpu 17.187 total
log-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.70s user 3.20s system 92% cpu 17.219 total
log-no-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.48s user 3.31s system 86% cpu 18.345 total
log-no-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.89s user 3.35s system 86% cpu 18.730 total
log-no-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.84s user 3.41s system 86% cpu 18.820 total
log-no-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.63s user 3.23s system 84% cpu 18.831 total
log-no-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.76s user 3.41s system 84% cpu 19.026 total
log-no-moving-expire:tar jxf /dev/shm/linux-2.6.38.3.tar.bz2  12.72s user 3.29s system 86% cpu 18.597 total

log-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.71s system 9% cpu 19.019 total
log-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.77s system 9% cpu 19.053 total
log-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.79s system 9% cpu 19.238 total
log-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.80s system 9% cpu 19.227 total
log-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.76s system 9% cpu 19.439 total
log-no-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.65s system 8% cpu 20.518 total
log-no-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.73s system 8% cpu 20.693 total
log-no-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.78s system 8% cpu 20.745 total
log-no-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.72s system 8% cpu 20.369 total
log-no-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.74s system 8% cpu 20.682 total
log-no-moving-expire:dd if=/dev/zero of=/fs/zero bs=1M count=1000  0.00s user 1.74s system 8% cpu 20.593 total

Thanks,
Fengguang
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