On 6/15/21 8:21 AM, Alexander Kanavin wrote:
On Tue, 15 Jun 2021 at 10:55, Alexander Kanavin <[email protected]
<mailto:[email protected]>> wrote:
On Tue, 15 Jun 2021 at 10:48, Richard Purdie
<[email protected]
<mailto:[email protected]>> wrote:
I appreciate the desire simply to delete/disable anything that
causes issues
but in this case I draw the line and my answer is no. It works
fine in the
vast majority of usage.
But where are the benchmarks that show it's actually beneficial? And
commitment from someone to maintain it and address open issues
(there are more than just this one)?
I went ahead and ran some quick benchmarks myself. Specifically:
1. Running 'free' after things have settled down at boot:
a) without prelink
core-image-sato-sdk
total used free shared buff/cache
available
Mem: 489352 152104 236284 472 100964
323824
core-image-ptest-fast
total used free shared buff/cache
available
Mem: 1004680 43456 927688 256 33536
941156
b) with prelink
core-image-sato-sdk
total used free shared buff/cache
available
Mem: 489352 153048 235544 468 100760
322900
core-image-ptest-fast
total used free shared buff/cache
available
Mem: 1004680 44444 928128 256 32108
940168
2. Running -c testimage
a) without prelink
core-image-sato-sdk () - Ran 66 tests in 96.693s
core-image-sato-sdk () - Ran 66 tests in 96.469s
core-image-sato-sdk () - Ran 66 tests in 94.994s
core-image-ptest-fast () - Ran 66 tests in 583.767s
core-image-ptest-fast () - Ran 66 tests in 576.564s
core-image-ptest-fast () - Ran 66 tests in 576.797s
b) with prelink
core-image-sato-sdk () - Ran 66 tests in 96.390s
core-image-sato-sdk () - Ran 66 tests in 96.615s
core-image-sato-sdk () - Ran 66 tests in 95.596s
core-image-ptest-fast () - Ran 66 tests in 576.248s
core-image-ptest-fast () - Ran 66 tests in 574.618s
core-image-ptest-fast () - Ran 66 tests in 576.760s
I think the advantage is not on high end CPUs but more on less powerful
ones, so perhaps trying it on something like rpi0 or lower would be good
So the memory usage is actually *better* without prelink. And any timing
benefits are lost in statistical noise, in these tests at least.
So I do not think it is wrong to question the usefulness of this
feature. I'd like to hear Mark's take on this, as prelink-cross is
primarily his work, he's put a lot of effort into it, and I would want
to know where the benefits are. Note that Red Hat abandoned prelink in
2013, and prelink-cross likewise hasn't seen any commits for two years.
Alex
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