Am 01.11.2019 um 15:01 hat Max Reitz geschrieben: > On 01.11.19 13:40, Eric Blake wrote: > > On 11/1/19 11:00 AM, Max Reitz wrote: > >> This reverts commit c8bb23cbdbe32f5c326365e0a82e1b0e68cdcd8a. > >> > >> This commit causes fundamental performance problems on XFS (because > >> fallocate() stalls the AIO pipeline), and as such it is not clear that > >> we should unconditionally enable this behavior. > >> > >> We expect subclusters to alleviate the performance penalty of small > >> writes to newly allocated clusters, so when we get them, the originally > >> intended performance gain may actually no longer be significant. > >> > >> If we want to reintroduce something similar to c8bb23cbdbe, it will > >> require extensive benchmarking on various systems with subclusters > >> enabled. > >> > >> Cc: qemu-sta...@nongnu.org > >> Signed-off-by: Max Reitz <mre...@redhat.com> > >> --- > > > >> +++ b/qapi/block-core.json > >> @@ -3304,8 +3304,6 @@ > >> # > >> # @cor_write: a write due to copy-on-read (since 2.11) > >> # > >> -# @cluster_alloc_space: an allocation of file space for a cluster > >> (since 4.1) > >> -# > >> # @none: triggers once at creation of the blkdebug node (since 4.1) > > > > Deleting released qapi is not backwards-compatible. > > Right. :-/ > > I’ll just not make changes to the QAPI schema. It doesn’t hurt to leave > this in.
Why would it be incompatible to drop an enum value that is only ever used in output and that QEMU doesn't generate? Kevin
signature.asc
Description: PGP signature
