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+<BODY>
+<H1>YAFFS2</H1>
+<H4>Summary</H4>
+<P>The original motivation for YAFFS 2 was to add support for the new
+NAND with 2kB pages instead of 512-byte pages and strictly sequential
+page writing order.
+</P>
+<P>To achieve this, a new design is used which also realises the
+following benefits:</P>
+<UL>
+ <LI><P>zero page rewrites, which means faster operation. (YAFFS1
+ uses a single rewrite in the spare area to delete a page).</P>
+ <LI><P>ability to exploit simultaneous page programming on some
+ chips.</P>
+ <LI><P>improves performance relative to YAFFS1 speed(write:1.5x to
+ 5x, delete: 4x, garbage collection: 2x)</P>
+ <LI><P>lower RAM footprint (approx. 25% to 50% of YAFFS1, depending
+ on chunk size used).</P>
+ <LI><P>Can support Toshiba/Sandisk MLC parts.</P>
+ <LI><P>Runtime selection between various chunk sizes.</P>
+</UL>
+<P>Most of YAFFS and YAFFS2 code is common, therefore the code will
+likely be kept common with YAFFS vs YAFFS2 being run-time selected.</P>
+<H4>Method</H4>
+<P>The main philosophical difference between YAFFS and YAFFS2 is how
+discarded status is tracked. Since we can't do any re-writing, we
+can't use the "discarded" flags in YAFFS2.</P>
+<P>Instead YAFFS2 uses two mechanisms to resolve data state.</P>
+<UL>
+ <LI><P>YAFFS2 chunks have more tag information, including a block
+ sequence Id. From that we can determine the chunk sequence Id since
+ the chunks are allocated sequentially in a block. Thus we always
+ know the patch order for all chunks in the system.</P>
+ <LI><P>The above helps us track stale -vs- fresh data, but does not
+ help determine when a file/object is deleted. Deletion is achieved
+ by moving the object to the "unlinked" directory. We also
+ keep track of the number of chunks (both stale and current) in the
+ system for each object. While this number indicates that there are
+ still chunks associated with this object we keep the deletion
+ record. When the last trace of the object has been really erased
+ from NAND, we can forget about the deletion record too.
+ </P>
+ <LI><P>Since there is no deletion, a resize (shrinking) of a file
+ will still have valid data chunks past the end of file on the NAND.
+ However, we write a new ObjectHeader at the time of the resize,
+ therefore this shows the shrunken file size.</P>
+</UL>
+<P>This changes erasure slightly:</P>
+<UL>
+ <LI><P>During garbage collection we can't just look at chunk state
+ flags, instead we must read the tags of each chunk to determine
+ which object's chunk count we must decrement. This step must also be
+ performed when a block is erased (as part of deletion).</P>
+</UL>
+<P>This makes erasure & garbage collection more expensive (by
+adding reads), but remember that ion YAFFS2 we don't need to do page
+deletions which are much more expensive operations. Thus, all-up
+YAFFS2 wins.</P>
+<H4>Tag structure</H4>
+<P>Each chunk in YAFFS2 has the following information:</P>
+<TABLE WIDTH=100% BORDER=1 CELLPADDING=4 CELLSPACING=3>
+ <COL WIDTH=45*>
+ <COL WIDTH=83*>
+ <COL WIDTH=64*>
+ <COL WIDTH=64*>
+ <THEAD>
+ <TR VALIGN=TOP>
+ <TH WIDTH=18%>
+ <P>Field</P>
+ </TH>
+ <TH WIDTH=32%>
+ <P>Comment</P>
+ </TH>
+ <TH WIDTH=25%>
+ <P>Size for 1kb chunks</P>
+ </TH>
+ <TH WIDTH=25%>
+ <P>Size for 2kB chunks</P>
+ </TH>
+ </TR>
+ </THEAD>
+ <TBODY>
+ <TR VALIGN=TOP>
+ <TD WIDTH=18%>
+ <P>blockState</P>
+ </TD>
+ <TD WIDTH=32%>
+ <P>Block state. non-0xFF for bad block</P>
+ </TD>
+ <TD WIDTH=25%>
+ <P>1 byte</P>
+ </TD>
+ <TD WIDTH=25%>
+ <P>1 byte</P>
+ </TD>
+ </TR>
+ <TR VALIGN=TOP>
+ <TD WIDTH=18%>
+ <P>chunkId</P>
+ </TD>
+ <TD WIDTH=32%>
+ <P>32-bit chunk Id</P>
+ </TD>
+ <TD WIDTH=25%>
+ <P>4 bytes</P>
+ </TD>
+ <TD WIDTH=25%>
+ <P>4 bytes</P>
+ </TD>
+ </TR>
+ <TR VALIGN=TOP>
+ <TD WIDTH=18%>
+ <P>objectId</P>
+ </TD>
+ <TD WIDTH=32%>
+ <P>32-bit object Id</P>
+ </TD>
+ <TD WIDTH=25%>
+ <P>4 bytes</P>
+ </TD>
+ <TD WIDTH=25%>
+ <P>4 bytes</P>
+ </TD>
+ </TR>
+ <TR VALIGN=TOP>
+ <TD WIDTH=18%>
+ <P>nBytes</P>
+ </TD>
+ <TD WIDTH=32%>
+ <P>Number of data bytes in this chunk</P>
+ </TD>
+ <TD WIDTH=25%>
+ <P>2 bytes</P>
+ </TD>
+ <TD WIDTH=25%>
+ <P>2 bytes</P>
+ </TD>
+ </TR>
+ <TR VALIGN=TOP>
+ <TD WIDTH=18%>
+ <P>blockSequence</P>
+ </TD>
+ <TD WIDTH=32%>
+ <P>sequence number for this block</P>
+ </TD>
+ <TD WIDTH=25%>
+ <P>4 bytes</P>
+ </TD>
+ <TD WIDTH=25%>
+ <P>4 bytes</P>
+ </TD>
+ </TR>
+ <TR VALIGN=TOP>
+ <TD WIDTH=18%>
+ <P>tagsEcc</P>
+ </TD>
+ <TD WIDTH=32%>
+ <P>ECC on tags area</P>
+ </TD>
+ <TD WIDTH=25%>
+ <P>3 bytes</P>
+ </TD>
+ <TD WIDTH=25%>
+ <P>3 bytes</P>
+ </TD>
+ </TR>
+ <TR VALIGN=TOP>
+ <TD WIDTH=18%>
+ <P>ecc</P>
+ </TD>
+ <TD WIDTH=32%>
+ <P>ECC, 3 bytes/256 bytes of data</P>
+ </TD>
+ <TD WIDTH=25%>
+ <P>12 bytes</P>
+ </TD>
+ <TD WIDTH=25%>
+ <P>24 bytes</P>
+ </TD>
+ </TR>
+ <TR VALIGN=TOP>
+ <TD WIDTH=18%>
+ <P><B>Total</B></P>
+ </TD>
+ <TD WIDTH=32%>
+ <P><BR>
+ </P>
+ </TD>
+ <TD WIDTH=25%>
+ <P ALIGN=LEFT><B>30 bytes</B></P>
+ </TD>
+ <TD WIDTH=25%>
+ <P><B>42 bytes</B></P>
+ </TD>
+ </TR>
+ </TBODY>
+</TABLE>
+<P><BR><BR>
+</P>
+<P>To get enough spare bytes for this tagging structure requires a
+chunk-size of at least 1kB. YAFFS1 is still used for 512-byte chunk
+sizes.</P>
+<P>The blockSequence increments each time a block is allocated. (ie.
+the first block allocated is block 1, and so on).</P>
+<H4>Scanning</H4>
+<P>The only reason we need to keep track of data status on NAND is to
+be able to recreate the file system state during scanning. Since we
+no longer have chunk deletion status flags we use a slightly
+different process for scanning a YAFFS2 system.</P>
+<P>In effect, YAFFS2 recreates its state by "replaying the
+tape". ie. it scans the chunks in their allocation order (block
+sequence Id order) rather than in their order on the media. This
+implies that at start up, the blocks must be read and their block
+sequence determined.</P>
+<H4>Performance</H4>
+<P>These numbers are indicative of relative performance. These only
+apply to the NAND data transfer and do not include other overheads.</P>
+<P>As an example, read/write cycle times of 100nS are used (though
+NAND can typically do 50nS), "seek time" of 10uS and
+program time of 200uS. Mileage will vary.</P>
+<P>NB x16 means using a 16-bit bus. Clearly this cuts down on data
+transfer time relative to an 8-bit bus.</P>
+<P>Times for 2kB read(units of 1uS).</P>
+<TABLE WIDTH=937 BORDER=1 CELLPADDING=4 CELLSPACING=3>
+ <COL WIDTH=175>
+ <COL WIDTH=176>
+ <COL WIDTH=177>
+ <COL WIDTH=176>
+ <COL WIDTH=173>
+ <THEAD>
+ <TR VALIGN=TOP>
+ <TH WIDTH=175>
+ <P>Operation</P>
+ </TH>
+ <TH WIDTH=176>
+ <P>YAFFS1</P>
+ </TH>
+ <TH WIDTH=177>
+ <P>YAFFS2 (512b pages)</P>
+ </TH>
+ <TH WIDTH=176>
+ <P>YAFFS2 (2kB pages)</P>
+ </TH>
+ <TH WIDTH=173>
+ <P>YAFFS2(2kB pages, x16)</P>
+ </TH>
+ </TR>
+ </THEAD>
+ <TBODY>
+ <TR>
+ <TD WIDTH=175 VALIGN=TOP>
+ <P>Seek
+ </P>
+ </TD>
+ <TD WIDTH=176 VALIGN=BOTTOM SDVAL="40" SDNUM="5129;">
+ <P ALIGN=RIGHT>40</P>
+ </TD>
+ <TD WIDTH=177 VALIGN=BOTTOM SDVAL="40" SDNUM="5129;">
+ <P ALIGN=RIGHT>40</P>
+ </TD>
+ <TD WIDTH=176 VALIGN=BOTTOM SDVAL="10" SDNUM="5129;">
+ <P ALIGN=RIGHT>10</P>
+ </TD>
+ <TD WIDTH=173 VALIGN=BOTTOM SDVAL="10" SDNUM="5129;">
+ <P ALIGN=RIGHT>10</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=175 VALIGN=TOP>
+ <P>Read</P>
+ </TD>
+ <TD WIDTH=176 VALIGN=BOTTOM SDVAL="220" SDNUM="5129;">
+ <P ALIGN=RIGHT>220</P>
+ </TD>
+ <TD WIDTH=177 VALIGN=BOTTOM SDVAL="220" SDNUM="5129;">
+ <P ALIGN=RIGHT>220</P>
+ </TD>
+ <TD WIDTH=176 VALIGN=BOTTOM SDVAL="220" SDNUM="5129;">
+ <P ALIGN=RIGHT>220</P>
+ </TD>
+ <TD WIDTH=173 VALIGN=BOTTOM SDVAL="110" SDNUM="5129;">
+ <P ALIGN=RIGHT>110</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=175 VALIGN=TOP>
+ <P>Total</P>
+ </TD>
+ <TD WIDTH=176 VALIGN=BOTTOM SDVAL="260" SDNUM="5129;">
+ <P ALIGN=RIGHT>260</P>
+ </TD>
+ <TD WIDTH=177 VALIGN=BOTTOM SDVAL="260" SDNUM="5129;">
+ <P ALIGN=RIGHT>260</P>
+ </TD>
+ <TD WIDTH=176 VALIGN=BOTTOM SDVAL="230" SDNUM="5129;">
+ <P ALIGN=RIGHT>230</P>
+ </TD>
+ <TD WIDTH=173 VALIGN=BOTTOM SDVAL="120" SDNUM="5129;">
+ <P ALIGN=RIGHT>120</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=175 VALIGN=TOP>
+ <P>MB/s</P>
+ </TD>
+ <TD WIDTH=176 VALIGN=BOTTOM SDVAL="7.6" SDNUM="5129;">
+ <P ALIGN=RIGHT>7.6</P>
+ </TD>
+ <TD WIDTH=177 VALIGN=BOTTOM SDVAL="7.6" SDNUM="5129;">
+ <P ALIGN=RIGHT>7.6</P>
+ </TD>
+ <TD WIDTH=176 VALIGN=BOTTOM SDVAL="8.7" SDNUM="5129;">
+ <P ALIGN=RIGHT>8.7</P>
+ </TD>
+ <TD WIDTH=173 VALIGN=BOTTOM SDVAL="16.7" SDNUM="5129;">
+ <P ALIGN=RIGHT>16.7</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=175 VALIGN=TOP>
+ <P>Relative speed</P>
+ </TD>
+ <TD WIDTH=176 VALIGN=BOTTOM SDVAL="1" SDNUM="5129;">
+ <P ALIGN=RIGHT>1</P>
+ </TD>
+ <TD WIDTH=177 VALIGN=BOTTOM SDVAL="1" SDNUM="5129;">
+ <P ALIGN=RIGHT>1</P>
+ </TD>
+ <TD WIDTH=176 VALIGN=BOTTOM SDVAL="1.1" SDNUM="5129;">
+ <P ALIGN=RIGHT>1.1</P>
+ </TD>
+ <TD WIDTH=173 VALIGN=BOTTOM SDVAL="2.2" SDNUM="5129;">
+ <P ALIGN=RIGHT>2.2</P>
+ </TD>
+ </TR>
+ </TBODY>
+</TABLE>
+<P><BR><BR>
+</P>
+<P>Times for 2kB writes(units of 1uS).</P>
+<TABLE WIDTH=100% BORDER=1 CELLPADDING=4 CELLSPACING=3>
+ <COL WIDTH=51*>
+ <COL WIDTH=51*>
+ <COL WIDTH=51*>
+ <COL WIDTH=51*>
+ <COL WIDTH=51*>
+ <THEAD>
+ <TR VALIGN=TOP>
+ <TH WIDTH=20%>
+ <P>Operation</P>
+ </TH>
+ <TH WIDTH=20%>
+ <P>YAFFS1</P>
+ </TH>
+ <TH WIDTH=20%>
+ <P>YAFFS2 (512b pages)</P>
+ </TH>
+ <TH WIDTH=20%>
+ <P>YAFFS2 (2kB pages)</P>
+ </TH>
+ <TH WIDTH=20%>
+ <P>YAFFS2(2kB pages, x16)</P>
+ </TH>
+ </TR>
+ </THEAD>
+ <TBODY>
+ <TR>
+ <TD WIDTH=20% VALIGN=TOP>
+ <P>Seek</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="40" SDNUM="5129;">
+ <P ALIGN=RIGHT>40</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="40" SDNUM="5129;">
+ <P ALIGN=RIGHT>40</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="10" SDNUM="5129;">
+ <P ALIGN=RIGHT>10</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="10" SDNUM="5129;">
+ <P ALIGN=RIGHT>10</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=20% VALIGN=TOP>
+ <P>Program</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="800" SDNUM="5129;">
+ <P ALIGN=RIGHT>800</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="800" SDNUM="5129;">
+ <P ALIGN=RIGHT>800</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="200" SDNUM="5129;">
+ <P ALIGN=RIGHT>200</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="200" SDNUM="5129;">
+ <P ALIGN=RIGHT>200</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=20% VALIGN=TOP>
+ <P>Seek</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="40" SDNUM="5129;">
+ <P ALIGN=RIGHT>40</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="40" SDNUM="5129;">
+ <P ALIGN=RIGHT>40</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="10" SDNUM="5129;">
+ <P ALIGN=RIGHT>10</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="10" SDNUM="5129;">
+ <P ALIGN=RIGHT>10</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=20% VALIGN=TOP>
+ <P>Read</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="220" SDNUM="5129;">
+ <P ALIGN=RIGHT>220</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="220" SDNUM="5129;">
+ <P ALIGN=RIGHT>220</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="220" SDNUM="5129;">
+ <P ALIGN=RIGHT>220</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="110" SDNUM="5129;">
+ <P ALIGN=RIGHT>110</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=20% VALIGN=TOP>
+ <P>Total</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="1320" SDNUM="5129;">
+ <P ALIGN=RIGHT>1320</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="1320" SDNUM="5129;">
+ <P ALIGN=RIGHT>1320</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="660" SDNUM="5129;">
+ <P ALIGN=RIGHT>660</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="440" SDNUM="5129;">
+ <P ALIGN=RIGHT>440</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=20% VALIGN=TOP>
+ <P>MB/s</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="1.5" SDNUM="5129;">
+ <P ALIGN=RIGHT>1.5</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="1.5" SDNUM="5129;">
+ <P ALIGN=RIGHT>1.5</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="3" SDNUM="5129;">
+ <P ALIGN=RIGHT>3</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="4.5" SDNUM="5129;">
+ <P ALIGN=RIGHT>4.5</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=20% VALIGN=TOP>
+ <P>Relative speed</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="1" SDNUM="5129;">
+ <P ALIGN=RIGHT>1</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="1" SDNUM="5129;">
+ <P ALIGN=RIGHT>1</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="2" SDNUM="5129;">
+ <P ALIGN=RIGHT>2</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="3" SDNUM="5129;">
+ <P ALIGN=RIGHT>3</P>
+ </TD>
+ </TR>
+ </TBODY>
+</TABLE>
+<P><BR><BR>
+</P>
+<P>Times for 1MB delete (units of 1uS).</P>
+<TABLE WIDTH=100% BORDER=1 CELLPADDING=4 CELLSPACING=3>
+ <COL WIDTH=51*>
+ <COL WIDTH=51*>
+ <COL WIDTH=51*>
+ <COL WIDTH=51*>
+ <COL WIDTH=51*>
+ <THEAD>
+ <TR VALIGN=TOP>
+ <TH WIDTH=20%>
+ <P>Operation</P>
+ </TH>
+ <TH WIDTH=20%>
+ <P>YAFFS1</P>
+ </TH>
+ <TH WIDTH=20%>
+ <P>YAFFS2 (512b pages)</P>
+ </TH>
+ <TH WIDTH=20%>
+ <P>YAFFS2 (2kB pages)</P>
+ </TH>
+ <TH WIDTH=20%>
+ <P>YAFFS2(2kB pages, x16)</P>
+ </TH>
+ </TR>
+ </THEAD>
+ <TBODY>
+ <TR>
+ <TD WIDTH=20% VALIGN=TOP>
+ <P>Seek</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="20480" SDNUM="5129;">
+ <P ALIGN=RIGHT>20480</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="0" SDNUM="5129;">
+ <P ALIGN=RIGHT>0</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="0" SDNUM="5129;">
+ <P ALIGN=RIGHT>0</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="0" SDNUM="5129;">
+ <P ALIGN=RIGHT>0</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=20% VALIGN=TOP>
+ <P>Program</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="409600" SDNUM="5129;">
+ <P ALIGN=RIGHT>409600</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="0" SDNUM="5129;">
+ <P ALIGN=RIGHT>0</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="0" SDNUM="5129;">
+ <P ALIGN=RIGHT>0</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="0" SDNUM="5129;">
+ <P ALIGN=RIGHT>0</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=20% VALIGN=TOP>
+ <P>Erase</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="128000" SDNUM="5129;">
+ <P ALIGN=RIGHT>128000</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="128000" SDNUM="5129;">
+ <P ALIGN=RIGHT>128000</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="16000" SDNUM="5129;">
+ <P ALIGN=RIGHT>16000</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="16000" SDNUM="5129;">
+ <P ALIGN=RIGHT>16000</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=20% VALIGN=TOP>
+ <P>Total</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="558080" SDNUM="5129;">
+ <P ALIGN=RIGHT>558080</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="128000" SDNUM="5129;">
+ <P ALIGN=RIGHT>128000</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="16000" SDNUM="5129;">
+ <P ALIGN=RIGHT>16000</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="16000" SDNUM="5129;">
+ <P ALIGN=RIGHT>16000</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=20% VALIGN=TOP>
+ <P>MB/s</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="1.8" SDNUM="5129;">
+ <P ALIGN=RIGHT>1.8</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="7.8" SDNUM="5129;">
+ <P ALIGN=RIGHT>7.8</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="62.5" SDNUM="5129;">
+ <P ALIGN=RIGHT>62.5</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="62.5" SDNUM="5129;">
+ <P ALIGN=RIGHT>62.5</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=20% VALIGN=TOP>
+ <P>Relative speed</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="1" SDNUM="5129;">
+ <P ALIGN=RIGHT>1</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="4" SDNUM="5129;">
+ <P ALIGN=RIGHT>4</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="34" SDNUM="5129;">
+ <P ALIGN=RIGHT>34</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="34" SDNUM="5129;">
+ <P ALIGN=RIGHT>34</P>
+ </TD>
+ </TR>
+ </TBODY>
+</TABLE>
+<P><BR><BR>
+</P>
+<P>Times for 1MB of garbage collection at 50% dirty (units of 1uS).</P>
+<TABLE WIDTH=100% BORDER=1 CELLPADDING=4 CELLSPACING=3>
+ <COL WIDTH=51*>
+ <COL WIDTH=51*>
+ <COL WIDTH=51*>
+ <COL WIDTH=51*>
+ <COL WIDTH=51*>
+ <THEAD>
+ <TR VALIGN=TOP>
+ <TH WIDTH=20%>
+ <P>Operation</P>
+ </TH>
+ <TH WIDTH=20%>
+ <P>YAFFS1</P>
+ </TH>
+ <TH WIDTH=20%>
+ <P>YAFFS2 (512b pages)</P>
+ </TH>
+ <TH WIDTH=20%>
+ <P>YAFFS2 (2kB pages)</P>
+ </TH>
+ <TH WIDTH=20%>
+ <P>YAFFS2(2kB pages, x16)</P>
+ </TH>
+ </TR>
+ </THEAD>
+ <TBODY>
+ <TR>
+ <TD WIDTH=20% VALIGN=TOP>
+ <P>Delete 1MB</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="558080" SDNUM="5129;">
+ <P ALIGN=RIGHT>558080</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="128000" SDNUM="5129;">
+ <P ALIGN=RIGHT>128000</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="16000" SDNUM="5129;">
+ <P ALIGN=RIGHT>16000</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="16000" SDNUM="5129;">
+ <P ALIGN=RIGHT>16000</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=20% VALIGN=TOP>
+ <P>Write 0.5MB</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="337920" SDNUM="5129;">
+ <P ALIGN=RIGHT>337920</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="337920" SDNUM="5129;">
+ <P ALIGN=RIGHT>337920</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="168960" SDNUM="5129;">
+ <P ALIGN=RIGHT>168960</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="112640" SDNUM="5129;">
+ <P ALIGN=RIGHT>112640</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=20% VALIGN=TOP>
+ <P>Total</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="896000" SDNUM="5129;">
+ <P ALIGN=RIGHT>896000</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="465920" SDNUM="5129;">
+ <P ALIGN=RIGHT>465920</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="184960" SDNUM="5129;">
+ <P ALIGN=RIGHT>184960</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="128640" SDNUM="5129;">
+ <P ALIGN=RIGHT>128640</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=20% VALIGN=TOP>
+ <P>MB/s</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="1.1" SDNUM="5129;">
+ <P ALIGN=RIGHT>1.1</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="2.1" SDNUM="5129;">
+ <P ALIGN=RIGHT>2.1</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="5.4" SDNUM="5129;">
+ <P ALIGN=RIGHT>5.4</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="7.7" SDNUM="5129;">
+ <P ALIGN=RIGHT>7.7</P>
+ </TD>
+ </TR>
+ <TR>
+ <TD WIDTH=20% VALIGN=TOP>
+ <P>Relative speed</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="1" SDNUM="5129;">
+ <P ALIGN=RIGHT>1</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="1.9" SDNUM="5129;">
+ <P ALIGN=RIGHT>1.9</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="4.9" SDNUM="5129;">
+ <P ALIGN=RIGHT>4.9</P>
+ </TD>
+ <TD WIDTH=20% VALIGN=BOTTOM SDVAL="7" SDNUM="5129;">
+ <P ALIGN=RIGHT>7</P>
+ </TD>
+ </TR>
+ </TBODY>
+</TABLE>
+<P><BR><BR>
+</P>
+<P>$Id: yaffs2.html,v 1.1 2002-11-26 01:15:37 charles Exp $</P>
+<P><BR><BR>
+</P>
+<P><BR><BR>
+</P>
+</BODY>
+</HTML>
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projects / yaffs / .git / blobdiff