lkml.org 
[lkml]   [2005]   [Apr]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC] CryptoAPI & Compression
David Woodhouse wrote:
> On Fri, 2005-04-01 at 18:57 +0400, Artem B. Bityuckiy wrote:
>
>>Yes, the compression will be better. But the implementation will be more
>>complicated.
>>We can try to use the "bound" functions to predict how many bytes to
>>pass to the deflate's input, but there is no guarantee they'll fit into
>>the output buffer. In this case we'll need to try again.
>
>
> Can we not predict the maximum number of bytes it'll take to flush the
> stream when we're not using Z_SYNC_FLUSH?

AFAIU, no. Zlib may eat a lot of input and do not produce much output, but
on Z_FINISH it may ask an undetermined amount of additional output space.
So, we must even regulate the amount of input we pass to zlib_deflate().
In case of Z_SYNC_FLUSH, things are more determined.

Another question, does JFFSx *really* need the peaces of a 4K page to be
independently uncompressable? It it wouldn't be required, we would achieve
better compression if we have saved the zstream state. :-) But it is too
late to change things at least for JFFS2.

--
Best Regards,
Artem B. Bityuckiy,
St.-Petersburg, Russia.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-04-06 13:31    [W:0.088 / U:2.936 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site