Re: [PATCH v2] new: Don't scan unchanged directories with no sub-directories

[David Bremner <david@tethera.net>]

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David Bremner <david@tethera.net> writes:

> Austin Clements <amdragon@MIT.EDU> writes:
>
>> This can substantially reduce the cost of notmuch new in some
>> situations, such as when the file system cache is cold or when the
>> Maildir is on NFS.
>
> On my desktop at home (a core i7 950) with spinning rust disks (and lvm
> on luks) this patch yields about a 7% slowdown in the intial new perf
> test
>
> from
>
> 			Wall(s)	Usr(s)	Sys(s)	Res(K)	In/Out(512B)
>   Initial notmuch new   579.60	348.86	14.26	217188	5330266/3501272
>
> to
>
> 			Wall(s)	Usr(s)	Sys(s)	Res(K)	In/Out(512B)
>   Initial notmuch new   620.51	368.62	15.48	217156	5330354/3416456
>
> On an SSD I don't detect a significant different (<0.5% speedup)

Seems like a false alarm. Averaging over 10 repetitions, the patched
version is about 1% faster. Unfortunately it points out that our
performance test suite should really do more than one repetition for
each test.


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#!/bin/bash

test_description='notmuch new'

. ./perf-test-lib.sh

time_start
for i in $(seq 1 10); do
    rm -rf ${MAIL_DIR}/.notmuch
    sudo /home/bremner/config/scripts/drop-caches
    time_run "notmuch new #$i" 'notmuch new'
done

time_done

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sync
sync
echo 1 > /proc/sys/vm/drop_caches
echo 2 > /proc/sys/vm/drop_caches
echo 3 > /proc/sys/vm/drop_caches