mtd/fs/jffs3 JFFS3design.tex,1.39,1.40

[Artem Bityuckiy]

Update of /home/cvs/mtd/fs/jffs3
In directory phoenix.infradead.org:/tmp/cvs-serv16314

Modified Files:
	JFFS3design.tex 
Log Message:
Updates.


Index: JFFS3design.tex
===================================================================
RCS file: /home/cvs/mtd/fs/jffs3/JFFS3design.tex,v
retrieving revision 1.39
retrieving revision 1.40
diff -u -r1.39 -r1.40
--- JFFS3design.tex	20 Apr 2005 14:23:51 -0000	1.39
+++ JFFS3design.tex	20 Apr 2005 16:10:38 -0000	1.40
@@ -310,7 +310,7 @@
 \end{enumerate}
 
 Of course there are a number of tradeoffs and we should find a balanced compromise
-solution,
+solution.
 
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 %
@@ -325,7 +325,7 @@
 
 \begin{itemize}
 \item data checkpoints which are associated with regular files;
-\item directory checkpoints which are associated with directories;
+\item directory checkpoints which are associated with directories.
 \end{itemize}
 
 %
@@ -379,6 +379,29 @@
 With the help of DCP JFFS3 need only keep in-core an array (or more
 precisely, a list of arrays) of DCP node references of files.
 
+The precise value of $R$ depends on the memory consumption requirements.
+The following table illustrates the dependency of the consumed memory and $R$
+for different file sizes (we assume each DCP reference takes 4 bytes).
+
+\begin{center}
+\begin{tabular}{lll}
+$R$     & File size & RAM required\\
+\hline
+512 KiB & 128 MiB   & 1 MiB\\
+1 MiB   & 128 MiB   & 0.5 MiB\\
+4 MiB   & 4 GiB     & 4 MiB\\
+8 MiB   & 4 GiB     & 1 MiB\\
+\end{tabular}
+\end{center}
+
+The $R$ value may be determined from the flash size and the desired RAM
+consumption limit and may be configurable.
+
+Since most files on the file system are small in size, we may facilitate
+faster changing of small files by making $R$ smaller for the beginning
+of files and and larger for the rest of files. I.e, 256~KiB for file
+ranges before 2~MiB and 8~MiB for ranges after 2~MiB.
+
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 % CHECKSUM