62777d825b
It is essential to choose a reasonable high value for 'msize' to avoid severely degraded file I/O performance. This parameter can only be chosen on client/guest side, and a Linux client defaults to an 'msize' of only 8192 if the user did not explicitly specify a value for 'msize', which results in very poor file I/O performance. Unfortunately many users are not aware that they should specify an appropriate value for 'msize' to avoid severe performance issues, so log a performance warning (with a QEMU wiki link explaining this issue in detail) on host side in that case to make it more clear. Currently a client cannot automatically pick a reasonable value for 'msize', because a good value for 'msize' depends on the file I/O potential of the underlying storage on host side, i.e. a feature invisible to the client, and even then a user would still need to trade off between performance profit and additional RAM costs, i.e. with growing 'msize' (RAM occupation), performance still increases, but performance delta will shrink continuously. Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com> Reviewed-by: Greg Kurz <groug@kaod.org> Message-Id: <e6fc84845c95816ad5baecb0abd6bfefdcf7ec9f.1599144062.git.qemu_oss@crudebyte.com> Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com> |
||
---|---|---|
.. | ||
9p-local.c | ||
9p-local.h | ||
9p-posix-acl.c | ||
9p-proxy.c | ||
9p-proxy.h | ||
9p-synth.c | ||
9p-synth.h | ||
9p-util.c | ||
9p-util.h | ||
9p-xattr-user.c | ||
9p-xattr.c | ||
9p-xattr.h | ||
9p.c | ||
9p.h | ||
codir.c | ||
cofile.c | ||
cofs.c | ||
coth.c | ||
coth.h | ||
coxattr.c | ||
Kconfig | ||
meson.build | ||
trace-events | ||
trace.h | ||
virtio-9p-device.c | ||
virtio-9p.h | ||
xen-9p-backend.c | ||
xen-9pfs.h |