Re: [Libguestfs] [nbdkit PATCH] sh: Prefer dd bs=1 over iflag=count_bytes
On Mon, Aug 17, 2020 at 11:35:39AM -0500, Eric Blake wrote:
While iflag=count_bytes combined with bs > 1 allows for more
efficient
operation, it is a feature of GNU dd, and not present on other
implementations such as BSD. Sticking to just POSIX features makes
things more portable.
I'm not very convinced by this. Maybe we should persuade
the BSD folk to implement this useful feature instead?
As one example:
diff --git a/docs/nbdkit-loop.pod b/docs/nbdkit-loop.pod
index 055b5750..b21c2212 100644
--- a/docs/nbdkit-loop.pod
+++ b/docs/nbdkit-loop.pod
@@ -120,7 +120,7 @@ creates a disk which contains a bad sector:
echo EIO Bad block >&2
exit 1
else
- dd if=/dev/zero count=$3 iflag=count_bytes
+ dd bs=1 if=/dev/zero count=$3
fi ;;
*) exit 2 ;;
esac
this change could be a killer for performance since the suggested size
of the disk is 64M.
Rich.
--
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