Signed-off-by: Leonid Bloch <lbloch@janustech.com>
---
 docs/qcow2-cache.txt | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/docs/qcow2-cache.txt b/docs/qcow2-cache.txt
index a0a1267482..43c0faaddb 100644
--- a/docs/qcow2-cache.txt
+++ b/docs/qcow2-cache.txt
@@ -110,11 +110,12 @@ How to configure the cache sizes
 Cache sizes can be configured using the -drive option in the
 command-line, or the 'blockdev-add' QMP command.
 
-There are three options available, and all of them take bytes:
+There are four options available:
 
-"l2-cache-size":         maximum size of the L2 table cache
-"refcount-cache-size":   maximum size of the refcount block cache
-"cache-size":            maximum size of both caches combined
+"l2-cache-size":         maximum size of the L2 table cache (bytes, K, M)
+"refcount-cache-size":   maximum size of the refcount block cache (bytes, K, M)
+"cache-size":            maximum size of both caches combined (bytes, K, M)
+"l2-cache-full":         make the L2 cache cover the full image (boolean)
 
 There are a few things that need to be taken into account:
 
@@ -130,6 +131,9 @@ 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.
 
+- If "l2-cache-full" is specified, QEMU will assign enough memory
+  to the L2 cache to cover the entire size of the image.
+
 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
-- 
2.14.1

On 07/24/2018 07:17 AM, Leonid Bloch wrote:
> Signed-off-by: Leonid Bloch <lbloch@janustech.com>
> ---
>   docs/qcow2-cache.txt | 12 ++++++++----
>   1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/docs/qcow2-cache.txt b/docs/qcow2-cache.txt
> index a0a1267482..43c0faaddb 100644
> --- a/docs/qcow2-cache.txt
> +++ b/docs/qcow2-cache.txt
> @@ -110,11 +110,12 @@ How to configure the cache sizes
>   Cache sizes can be configured using the -drive option in the
>   command-line, or the 'blockdev-add' QMP command.
>   
> -There are three options available, and all of them take bytes:
> +There are four options available:
>   
> -"l2-cache-size":         maximum size of the L2 table cache
> -"refcount-cache-size":   maximum size of the refcount block cache
> -"cache-size":            maximum size of both caches combined
> +"l2-cache-size":         maximum size of the L2 table cache (bytes, K, M)
> +"refcount-cache-size":   maximum size of the refcount block cache (bytes, K, M)
> +"cache-size":            maximum size of both caches combined (bytes, K, M)
> +"l2-cache-full":         make the L2 cache cover the full image (boolean)
>   
>   There are a few things that need to be taken into account:
>   

Worth mentioning that the first three can be combined (although usually 
you'll never specify more than 2; as specifying all 3 requires that you 
perform the correct addition), but that the third is mutually exclusive?

> @@ -130,6 +131,9 @@ 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.
>   
> +- If "l2-cache-full" is specified, QEMU will assign enough memory
> +  to the L2 cache to cover the entire size of the image.
> +
>   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
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

   On 07/24/2018 06:21 PM, Eric Blake wrote:

     On 07/24/2018 07:17 AM, Leonid Bloch wrote:

     Signed-off-by: Leonid Bloch [1]<lbloch@janustech.com>
     ---
       docs/qcow2-cache.txt | 12 ++++++++----
       1 file changed, 8 insertions(+), 4 deletions(-)
     diff --git a/docs/qcow2-cache.txt b/docs/qcow2-cache.txt
     index a0a1267482..43c0faaddb 100644
     --- a/docs/qcow2-cache.txt
     +++ b/docs/qcow2-cache.txt
     @@ -110,11 +110,12 @@ How to configure the cache sizes
       Cache sizes can be configured using the -drive option in the
       command-line, or the 'blockdev-add' QMP command.
       -There are three options available, and all of them take bytes:
     +There are four options available:
       -"l2-cache-size":         maximum size of the L2 table cache
     -"refcount-cache-size":   maximum size of the refcount block cache
     -"cache-size":            maximum size of both caches combined
     +"l2-cache-size":         maximum size of the L2 table cache (bytes,
     K, M)
     +"refcount-cache-size":   maximum size of the refcount block cache
     (bytes, K, M)
     +"cache-size":            maximum size of both caches combined
     (bytes, K, M)
     +"l2-cache-full":         make the L2 cache cover the full image
     (boolean)
         There are a few things that need to be taken into account:


     Worth mentioning that the first three can be combined (although
     usually you'll never specify more than 2; as specifying all 3
     requires that you perform the correct addition), but that the third
     is mutually exclusive?

   Actually, only 2 of the first 3 can be specified. But you're right, I
   need to write about mutual exclusivity in the docs. Will fix in v2.
   Thanks!

     @@ -130,6 +131,9 @@ 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.
       +- If "l2-cache-full" is specified, QEMU will assign enough memory
     +  to the L2 cache to cover the entire size of the image.
     +
       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

References

   1. mailto:lbloch@janustech.com