On 25-11-2014 11:03, Andriy Gapon wrote: > On 21/11/2014 22:25, Xin Li wrote: >> On 11/21/14 07:18, Andriy Gapon wrote: >>> On 13/10/2014 23:39, Xin LI wrote: >>>> Author: delphij Date: Mon Oct 13 20:39:51 2014 New Revision: >>>> 273060 URL: https://svnweb.freebsd.org/changeset/base/273060 >>>> >>>> Log: Use write_psize instead of write_asize when doing >>>> vdev_space_update. Without this change the accounting of L2ARC >>>> usage would be wrong and give 16EB free space because the number >>>> became negative and overflows. >>>> >>>> Obtained from: FreeNAS (issue #6239) >> >>> First, a link to the issue would be more convenient for reviewers. >>> Here it is https://bugs.freenas.org/issues/6239 >> >>> Then, I would like to see a technical explanation for this change. >>> I could not find any explanation here or in the FreeNAS issue or in >>> the FreeNAS commit. >> >>> As far as I can see, all calls to vdev_space_update() in the ARC >>> code are passed l2hdr->b_asize or a sum of b_asize fields of >>> multiple buffers. Thus, I am really surprised with this change and >>> would like to see reasoning behind it. >> >> Hmm I think you are right that my change doesn't make sense but I >> can't remember the details either and suggests there is some other >> issues that was covered up by this. > > Maybe you have some other changes in FreeNAS and the change in question is > supposed to work along with them? > > Meanwhile, perhaps the discussed commit needs to be reverted? > >> It looks like that I was confused because the L2ARC clock hand >> advances by buf_p_sz (unrelated but it should really be called >> buf_a_size) and the way we calculate allocated L2ARC free. > > Agree about 'a' vs 'p'. And, BTW, we have some related changes in ClusterHQ > that I will upstream. >
Not sure how this got resolved but I immediately recognise some of this since I run into this on one of my volumes. These are 2 ssd caches on a raidz2 pool, and they are certainly not 16EB. ........... cache - - - - - - diskid/DISK-S1ANNSADB75814Wp3 109G 187G 16.0E - 0% 172% diskid/DISK-S1ANNSADB75819Ep3 109G 166G 16.0E - 0% 152% --WjW _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
