+1 On Fri, Jan 6, 2017 at 7:36 AM, John Spray <jspray@xxxxxxxxxx> wrote: > On Fri, Jan 6, 2017 at 11:38 AM, kefu chai <tchaikov@xxxxxxxxx> wrote: >> hi cephers, >> >> libcommon is a convenient library and is statically linked into >> librados, librbd and libcephfs. and there are some static variables >> living in libcommon, for instance, the ones defined in lockdep.cc. so, >> we will have multiple copies of these global variables if an >> application is linked against librados and (librbd | libcephfs). the >> "ceph" cli does link against librados and libcephfs via the their >> python bindings. >> >> this incurs some problems: >> >> - cross reference each other's global variables: in my testbed, i ran >> into https://github.com/ceph/ceph/pull/12249#issuecomment-264105597. >> where libcephfs was referencing the lockdeps variables in librados >> when relinquishing a lock. when libcephfs tries to acquire this lock >> again, it found that this lock is *already* locked. >> - more memory foot print and disk space: apparently, libcommon is >> included by librados, librbd and libcephfs. so it's a waste to have >> multiple copies of libcommon if librbd and/or libcephfs are loaded >> into memory or installed onto disk. >> >> after turning libcommon into a shared library, these problems are solved. >> >> but yes, unlike librados and its friends, libcommon is not a user >> facing library, so we will not install it right under /usr/lib/. >> instead, it will be living in /usr/lib/ceph. please note, the erasure >> plugins are installed into /usr/lib/ceph/erasure-code/ and rados >> classes are installed into /usr/lib/rados-classes/. this follows the >> related section of FHS [1]. >> >> what do you think? > > +1 > > John > >> >> -- >> [1] http://www.pathname.com/fhs/pub/fhs-2.3.html#USRLIBLIBRARIESFORPROGRAMMINGANDPA >> >> -- >> Regards >> Kefu Chai >> -- >> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
