From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zdenek Kabelac Date: Wed, 23 Mar 2011 17:33:39 +0100 Subject: [PATCH 1/6] Pool locking code In-Reply-To: <4D8A1886.1090105@redhat.com> References: <1300888988.14527.28.camel@ubuntu> <4D8A098C.8060803@redhat.com> <1300893225.14527.37.camel@ubuntu> <4D8A1886.1090105@redhat.com> Message-ID: <4D8A20E3.5030809@redhat.com> List-Id: To: lvm-devel@redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Dne 23.3.2011 16:57, Zdenek Kabelac napsal(a): > Dne 23.3.2011 16:13, Joe Thornber napsal(a): >> On Wed, 2011-03-23 at 15:54 +0100, Zdenek Kabelac wrote: >>> Forget to answer the size question - >8MB is allocated by the VG >>> mempool when >>> set of simple linear 7200LVs on 1 PV are in use. >> >> So I think each snapshot/restore of a VG pool of that size is going to >> take ~0.1 seconds. So now my question is how many times are we >> expecting to happen during a typical tool invocation? Your previous >> reply suggested it happens just once? > > > If there would be just 1 vg read for 7200 activate call - obviously I'd not > need to play with this dm_pool locking :) > > So there is 7200 vg reads - which will use this one locked pool with my patch set: > > To give some time info here > (using my unoptimized gcc debug build on C2D 2.2GHz - but with few more > patches applied than current upstream) > > Deactivate 7200LV (7200 already active) > real 1m16.140s > user 0m5.686s > sys 0m31.410s > > > Deactivate 7200LV (non active) > real 0m2.121s > user 0m1.083s > sys 0m1.032s > > > Activate 7200 (non active) > real 2m19.324s > user 0m6.503s > sys 1m30.785s > > Activate 7200 (7200 already active) > real 0m10.945s > user 0m1.422s > sys 0m9.502s > I think good example could be this - when I disable mprotect-ing in my patchset - and enable crc checking with each dm_pool_restore (which should be similar to memcpy) (otherwise crc is checked only with final pool unlock) Deactivate 7200LV real 1m45.353s user 0m38.128s sys 0m27.395s Deactivate 7200LV real 0m36.948s user 0m35.284s sys 0m1.642s Activate 7200 (non active) real 2m31.065s user 0m37.740s sys 1m18.481s (here could be observed - thet mprotecting takes 12s) Activate 7200 (7200 already active) real 0m52.188s user 0m35.570s sys 0m16.563s So I'd estimate like 33seconds would be wasted. -- And to complete the picture - crc only with unlock - and without pool mprotect-ing - assuming this would be normal work. Deactivate 7200LV real 1m9.989s user 0m4.584s sys 0m26.882s Deactivate 7200LV real 0m2.119s user 0m1.087s sys 0m1.025s Activate 7200 (non active) real 2m11.363s user 0m4.696s sys 1m15.393s Activate 7200 (7200 already active) real 0m11.127s user 0m1.392s sys 0m9.669s Zdenek