Am 26.07.2018 um 16:27 hat Leonid Bloch geschrieben: > On 07/26/2018 01:02 PM, Kevin Wolf wrote: > > Am 25.07.2018 um 16:27 hat Leonid Bloch geschrieben: > > > Signed-off-by: Leonid Bloch <lbl...@janustech.com> > > > --- > > > docs/qcow2-cache.txt | 3 +++ > > > qemu-options.hx | 10 ++++++---- > > > 2 files changed, 9 insertions(+), 4 deletions(-) > > > > > > diff --git a/docs/qcow2-cache.txt b/docs/qcow2-cache.txt > > > index 8a09a5cc5f..3673f2be0e 100644 > > > --- a/docs/qcow2-cache.txt > > > +++ b/docs/qcow2-cache.txt > > > @@ -130,6 +130,9 @@ There are a few things that need to be taken into > > > account: > > > memory as possible to the L2 cache before increasing the refcount > > > cache size. > > > +- At most two of "l2-cache-size", "refcount-cache-size", and "cache-size" > > > + can be set simultaneously. > > > > The indentation is off here, the other list items have one space more. > > > > > Unlike L2 tables, refcount blocks are not used during normal I/O but > > > only during allocations and internal snapshots. In most cases they are > > > accessed sequentially (even during random guest I/O) so increasing the > > > diff --git a/qemu-options.hx b/qemu-options.hx > > > index b1bf0f485f..13ece21cb6 100644 > > > --- a/qemu-options.hx > > > +++ b/qemu-options.hx > > > @@ -752,15 +752,17 @@ image file) > > > @item cache-size > > > The maximum total size of the L2 table and refcount block caches in > > > bytes > > > -(default: 1048576 bytes or 8 clusters, whichever is larger) > > > > I think it would be good to still say something about the default. > > Maybe something like "default: the sum of l2-cache-size and > > refcount-cache-size"? > > Yes, that sounds good! > > > > > > @item l2-cache-size > > > -The maximum size of the L2 table cache in bytes > > > -(default: 4/5 of the total cache size) > > > +The maximum size of the L2 table cache. > > > > Why did you remove "in bytes" and add a period which the other options > > don't have? I prefer the old version of this line. > > I removed "in bytes" because it also accepts k, M, G, ... but on a second > thought, these are amounts of bytes as well, so changing back to the old > version. > > > > +(default: if cache-size is not defined - 1048576 bytes or 8 clusters, > > > whichever > > > +is larger; otherwise, as large as possible or needed within the > > > cache-size, > > > +while permitting the requested or the minimal refcount cache size) > > > @item refcount-cache-size > > > The maximum size of the refcount block cache in bytes > > > -(default: 1/5 of the total cache size) > > > +(default: 4 times the cluster size, or any portion of the cache-size, if > > > it is > > > +specified and large enough, left over after allocating the full L2 cache) > > > > I found the second part hard to understand. Maybe "4 times the cluster > > size; or if both cache-size and l2-cache-size are given, the part of > > the cache-size that is not used for the L2 cache yet."? > > That is not accurate. Because even if l2-cache-size is not given and > cache-size is large enough to accommodate enough L2 cache to cover the > entire image, plus the minimal amount of refcount cache with room to spare - > refcount cache will use all the rest of the cache-size.
Oh, you're right! I wasn't aware that we consider the image size there. > How about: > > "default: 4 times the cluster size; or if cache-size is specified, the part > of it which is not used for the L2 cache" Even simpler, easier to understand and more accurate. I like it. Kevin
