Date: Fri, 14 Apr 2017 12:58:59 -0700 From: "Ngie Cooper (yaneurabeya)" <yaneurabeya@gmail.com> To: Alan Somers <asomers@freebsd.org> Cc: Ngie Cooper <ngie@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org> Subject: Re: svn commit: r316938 - head/sbin/savecore Message-ID: <499FA6FF-E691-4941-B96C-3806072D14AA@gmail.com> In-Reply-To: <CAOtMX2gPHWRGiE9UA5AevZz=cTv_qksAWX0H-xRjDEHp0huCVg@mail.gmail.com> References: <201704141941.v3EJfmCW003347@repo.freebsd.org> <CAOtMX2gPHWRGiE9UA5AevZz=cTv_qksAWX0H-xRjDEHp0huCVg@mail.gmail.com>
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[-- Attachment #1 --] > On Apr 14, 2017, at 12:49, Alan Somers <asomers@freebsd.org> wrote: > > On Fri, Apr 14, 2017 at 1:41 PM, Ngie Cooper <ngie@freebsd.org> wrote: >> Author: ngie >> Date: Fri Apr 14 19:41:48 2017 >> New Revision: 316938 >> URL: https://svnweb.freebsd.org/changeset/base/316938 >> >> Log: >> savecore: fix space calculation with respect to `minfree` in check_space(..) >> >> - Use strtoll(3) instead of atoi(3), because atoi(3) limits the >> representable data to INT_MAX. Check the values received from >> strtoll(3), trimming trailing whitespace off the end to maintain >> POLA. >> - Use `KiB` instead of `kB` when describing free space, total space, >> etc. I am now fully aware of `KiB` being the IEC standard for 1024 >> bytes and `kB` being the IEC standard for 1000 bytes. >> - Store available number of KiB in `available` so it can be more >> easily queried and compared to ensure that there are enough KiB to >> store the dump image on disk. >> - Print out the reserved space on disk, per `minfree`, so end-users >> can troubleshoot why check_space(..) is reporting that there isn't >> enough free space. >> >> MFC after: 7 weeks >> Reviewed by: Anton Rang <rang@acm.com> (earlier diff), cem (earlier diff) >> Tested with: positive/negative cases (see review); make tinderbox >> Sponsored by: Dell EMC Isilon >> Differential Revision: D10379 > > The free space calculation is still uselessly conservative, because it > doesn't account for the fact that core dumps will always be either > spare or compressed. The result is that savecore will frequently > refuse to save corefiles even when there's plenty of space. I > proposed removing the space check altogether in > https://reviews.freebsd.org/D2587. However, I agreed to wait until > after the compressed core dump feature was merged, because then mostly > accurate space checks will be possible. AFAIK the compressed core > dump feature still hasn't been finished. That CR concerns me. The whole being able to check how much space we have on disk before dumping is a wonderful tool because it prevents users from having /var/crash be full of truncated full dumps, text dumps, and/or mini dumps. The real problem that you’re bringing up is that the size being passed in to check_size(..) is wrong. It needs to be the on-disk size (which can be a pessimization from gzip/zlib), not the in-memory size of all of the dumped pages. Thanks for the note — this helps me with another related issue at $work that will likely prevent me from being able to write proper tests to test out panic dumps on OneFS :). Cheers! -Ngie [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Comment: GPGTools - https://gpgtools.org iQIcBAEBCgAGBQJY8SoDAAoJEPWDqSZpMIYV7voQAKbufDeLzoHSyypP7EJKI49d 3s+0YWJUpPNC6JSxxzMF5CBEJvdPYrjXlPsLiswrwjxwN9DhH3MipoO+KKwvH6q0 XU91WgtlgKoEb93DN7/SE1NeEDBwBT/v/iQYlay+jEQT8Oc7gZJk+FuVuuJBec6d Fx+r1tq7JYSUHUEHVyMBJj9v3n9CjGxm0Cf7g9bWICwJZto9gbwMxMsVeB9Wl37w i2l83PNRGbUy5fduu+xwYgDRfGV/1tA88zwT+bl87mX1TEMkExAO3ZVTbVgVktkc /hS6x/Ao1+l5EcbI/7sDJ20yW8hVv/XCkO+ysOCJNbWCb355BiQXypvFi/oCOTEl CO3+YOadHsPEArC5dbsczI+lTcH/e8pY0d+EteoN7b4UiOQkIn6+ZjfC7Zih36ZM kcvPG367Wdzjhcb5YJSqQEZ3nNHM5pVeHWnIr6Vc/ul1ECYNq/aRLPG1DGd+fhGa x3zVPhCj1ouq5Tb/lNbsAjCh5sOThRC6172Sn3V8vln673mr2ZNl/z+T8lmv6RHo FjYh7gQS3oorcrsPINBakEf9I8rzWVD7Xj4mMdfbUgS09rRyzVN53HDWGfUbWKzB z0LwE46P0IvofiYl+b8Q3FiZscag3MSn5dRadFeFe/F9DQG+mwG9jtjl/FL1o6XV AVe62xAQbTWB01VUPAbE =r1XN -----END PGP SIGNATURE-----
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