From: Fam Zheng <famz@redhat.com>
To: qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, Max Reitz <mreitz@redhat.com>,
qemu-block@nongnu.org
Subject: [Qemu-devel] [PATCH] qemu-img: Document copy offloading implications with -S and -c
Date: Wed, 11 Jul 2018 09:22:27 +0800 [thread overview]
Message-ID: <20180711012227.31600-1-famz@redhat.com> (raw)
Explicitly enabling zero detection or compression suppresses copy
offloading during convert. Document it.
Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
---
qemu-img.texi | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/qemu-img.texi b/qemu-img.texi
index aeb1b9e66c..5853cd18d1 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -96,7 +96,8 @@ will enumerate information about backing files in a disk image chain. Refer
below for further description.
@item -c
-indicates that target image must be compressed (qcow format only)
+indicates that target image must be compressed (qcow format only). If this
+option is used, copy offloading will not be attempted.
@item -h
with or without a command shows help and lists the supported formats
@@ -115,7 +116,8 @@ in case both @var{-q} and @var{-p} options are used.
indicates the consecutive number of bytes that must contain only zeros
for qemu-img to create a sparse image during conversion. This value is rounded
down to the nearest 512 bytes. You may use the common size suffixes like
-@code{k} for kilobytes.
+@code{k} for kilobytes. If this option is used, copy offloading will not be
+attempted.
@item -t @var{cache}
specifies the cache mode that should be used with the (destination) file. See
--
2.17.1
next reply other threads:[~2018-07-11 1:22 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-11 1:22 Fam Zheng [this message]
2018-07-11 10:24 ` [Qemu-devel] [PATCH] qemu-img: Document copy offloading implications with -S and -c Kevin Wolf
2018-07-11 13:27 ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
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