Well, ok, I flipped out a bit. Not the first time. Sorry. I'm a little off balance.
I intend to finish this patch on my way out the door, as I'm going to finish it anyway. Use it or not, doesn't matter. The code is simple and really already done, but these BBC extensions to JFFS2 had me a little off target for a few minutes, since it largely replaces the original JFFS2 code, but leaves the deprecated code sitting around for good looks. In a previous mail I described priority mode compression where the encoders are selected based on their rank. I should note that size mode is also available with JFFS2 BBC. I knew it was available in mkfs.jffs2, but looking at the fs/jffs2/compr.c source, it appeared as if it wasn't with JFFS2. Little did I know that source wasn't the post-BBC'd JFFS2 file system driver. Size mode iterates through available compressors, trying each one and selecting the best size. I just wanted to be correct here. For those worrying about LZMA speed, here's my analyais: 1.) Remember, post-install LZMA compression is not supported by this patch. Compression speed is therefore not an issue. However, when it is eventually added, it may improve the current write speed because you can replace 5 or so compressors with one. Also, with these measly 4Kb blocks, compression speed is hardly an issue with any algorithm. 2.) Decoding speed may be a little bit slower than ZLIB, but still it's going to be substantially faster than SquashFs-LZMA due to the smaller block size. It's plenty fast enough. Therefore, I am pretty certain that LZMA decoding speed won't be an issue, and in the future LZMA encoding speed won't be an issue either. That said, this patch really should be done 'up stream' from Free/OpenWrt. I don't know why this hasn't been done before, maybe nobody has thought of just adding the decoder and instead focused on why adding the LZMA C++ encoder is problematic. I'm still really new to the linux kernel, but I think I can pull this off successfully without any big issues. I'll send target/ style patches to patch the JFFS2-BBC code. -- Jeremy Collake (db90h) _______________________________________________ freewrt-developers mailing list [email protected] https://www.freewrt.org/lists/listinfo/freewrt-developers
