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

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+From: David Bremner <david@tethera.net>\r
+Newsgroups: \r
+To: Austin Clements <amdragon@MIT.EDU>, notmuch@notmuchmail.org\r
+Subject: Re: [PATCH v2] new: Don't scan unchanged directories with no\r
+       sub-directories\r
+In-Reply-To: <878uxgvqh2.fsf@zancas.localnet>\r
+References: <20131024210837.GH20337@mit.edu>\r
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+Date: Sat, 26 Oct 2013 08:52:55 -0300\r
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+\r
+--=-=-=\r
+Content-Type: text/plain\r
+\r
+David Bremner <david@tethera.net> writes:\r
+\r
+> Austin Clements <amdragon@MIT.EDU> writes:\r
+>\r
+>> This can substantially reduce the cost of notmuch new in some\r
+>> situations, such as when the file system cache is cold or when the\r
+>> Maildir is on NFS.\r
+>\r
+> On my desktop at home (a core i7 950) with spinning rust disks (and lvm\r
+> on luks) this patch yields about a 7% slowdown in the intial new perf\r
+> test\r
+>\r
+> from\r
+>\r
+>                      Wall(s) Usr(s)  Sys(s)  Res(K)  In/Out(512B)\r
+>   Initial notmuch new   579.60       348.86  14.26   217188  5330266/3501272\r
+>\r
+> to\r
+>\r
+>                      Wall(s) Usr(s)  Sys(s)  Res(K)  In/Out(512B)\r
+>   Initial notmuch new   620.51       368.62  15.48   217156  5330354/3416456\r
+>\r
+> On an SSD I don't detect a significant different (<0.5% speedup)\r
+\r
+Seems like a false alarm. Averaging over 10 repetitions, the patched\r
+version is about 1% faster. Unfortunately it points out that our\r
+performance test suite should really do more than one repetition for\r
+each test.\r
+\r
+\r
+--=-=-=\r
+Content-Type: text/x-sh\r
+Content-Disposition: inline; filename=crunch.sh\r
+\r
+#!/bin/bash\r
+\r
+test_description='notmuch new'\r
+\r
+. ./perf-test-lib.sh\r
+\r
+time_start\r
+for i in $(seq 1 10); do\r
+    rm -rf ${MAIL_DIR}/.notmuch\r
+    sudo /home/bremner/config/scripts/drop-caches\r
+    time_run "notmuch new #$i" 'notmuch new'\r
+done\r
+\r
+time_done\r
+\r
+--=-=-=\r
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+--=-=-=--\r