https://bugzilla.samba.org/show_bug.cgi?id=10552
--- Comment #1 from John Pierman <haqt...@gmail.com> 2014-04-17 12:34:03 UTC --- Confirmed: Without -z avg over 3 runs (real 0m5.998s) With -z avg over 3 runs (real 0m8.490s) On Mon, Apr 14, 2014 at 4:10 PM, <samba-b...@samba.org> wrote: > https://bugzilla.samba.org/show_bug.cgi?id=10552 > > Summary: Sender checksum calculation significantly slower with > compression enabled > Product: rsync > Version: 3.1.1 > Platform: All > OS/Version: All > Status: NEW > Severity: normal > Priority: P5 > Component: core > AssignedTo: way...@samba.org > ReportedBy: dougmi...@cox.net > QAContact: rsync...@samba.org > > > I've noticed that with the -z option enabled, comparing two files that are > identical (or nearly so) but have different modification times takes > significantly longer than without the -z option. It looks like the entire > file > is compressed as the checksum is calculated even when no data needs to be > transmitted to the receiver. > > To replicate: > > Create test folders/files (using incompressible data to maximize effect): > mkdir a b > dd if=/dev/urandom of=a/a.tst bs=1M count=250 > cp a/a.tst b/ > > run rsync without compression: > touch a/a.tst > time rsync -av a/ b > > run rsync with compression: > touch a/a.tst > time rsync -avz a/ b > > The second time with the -z option will take significantly longer, even > though > the source and destination files are identical apart from the modification > times. I've also found that the latter uses much more CPU, but only on > one of > the two processes- the sender process I believe. > > Even when I added --skip-compress=tst, it made rsync much faster than -z > alone, > but it still took about 30% longer than omitting -z entirely. > > -- > Configure bugmail: https://bugzilla.samba.org/userprefs.cgi?tab=email > ------- You are receiving this mail because: ------- > You are the QA contact for the bug. > -- > Please use reply-all for most replies to avoid omitting the mailing list. > To unsubscribe or change options: > https://lists.samba.org/mailman/listinfo/rsync > Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html > -- Configure bugmail: https://bugzilla.samba.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the QA contact for the bug. -- Please use reply-all for most replies to avoid omitting the mailing list. To unsubscribe or change options: https://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
