[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v1 09/10] libxl: introduce libxl_retrieve_domain_configuration
Wei Liu writes ("Re: [PATCH v1 09/10] libxl: introduce libxl_retrieve_domain_configuration"): > On Thu, Jul 17, 2014 at 11:59:01AM +0100, Ian Campbell wrote: > > Also is there is any possibility that any of the operations needed to > > gather the updated configuration might take a long time. > > I think reading from xenstore and filesystem can be slow, in the sense > that if there's much contention on these two resources it could take > seconds to finish operations. For the purposes of libxl, slow functions are defined as follows (libxl_internal.h): * "Slow" functions includes any that might block on a guest or an * external script. More broadly, it includes any operations which * are sufficiently slow that an application might reasonably want to * initiate them, and then carry on doing something else, while the * operation completes. That is, a "fast" function must be fast * enough that we do not mind blocking all other management operations * on the same host while it completes. * * There are certain primitive functions which make a libxl operation * necessarily "slow" for API reasons. These are: * - awaiting xenstore watches (although read-modify-write xenstore * transactions are OK for fast functions) * - spawning subprocesses * - anything with a timeout Note that xenstore accesses are explicitly excluded. Ian. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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