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[[File:Lauterbach-eMMC-2-3.png|center|thumb|821x821px|With ftrace, no TRACE32 instrumentation]]
=== Conclusion =Logs analysis and conclusions ====No matter how the accesses to the e.MMC are traced, once the logs are available they can be processed thoroughly to produce reports that are very useful to analyze how the host actually operates the device. The following are some such reports from a test conducted on a e.MMC partition (<code>mmcblk0p1</code>) formatted with <code>ext4</code> file system: <pre class="board-terminal">mkfs.ext4 /dev/mmcblk0p1</pre> Please note that this formatting results in a 4 kByte block size:<pre class="board-terminal">root@imx8mqevk:~# dumpe2fs -x /dev/mmcblk0p1 dumpe2fs 1.43.5 (04-Aug-2017)Filesystem volume name: <none>...Block size: 4096...</pre>The ext4 block must not be confused with the e.MMC blocks, which are 512 bytes as per JEDEC specifications and are addressed according to the [https://en.wikipedia.org/wiki/Logical_block_addressing LBA] scheme. The analyzed workload is the result of a combination of different tools performing read and write accesses (<code>/mnt/mmc0</code> is the mount point of the partition of interest):<pre class="board-terminal">root@imx8mqevk:~# stressapptest -s 20 -f /mnt/mmc0/file1 -f /mnt/mmc0/file2root@imx8mqevk:~# find / -name "*" > /mnt/mmc0/find_results.txtroot@imx8mqevk:~# dd if=/dev/urandom of=/mnt/mmc0/dummyfile.bin bs=4k count=25000root@imx8mqevk:~# rm /mnt/mmc0/dummyfile.binroot@imx8mqevk:~# dd if=/dev/zero of=/mnt/mmc0/dummyfile.bin bs=4k count=25000root@imx8mqevk:~# sync</pre> The following chart 4kB (dd) 512B (streassapptest) Questo perché, non essendo specificato il parametro --write-block-size, dovrebbe valere il default: read_block_size_ = kSectorSize; // default 1 sector (512 bytes) write_block_size_ = kSectorSize; // this assumes read and write block size
==== Appendix 1: source code example ====
