On Mon, May 8, 2017 at 3:56 PM, marcin steć <stecenator@xxxxxxxxx> wrote: > Journal is not the reason. It's just the first one to hit the bottleneck. You are correct, it's primarily a kernel issue. The good news this has improved with Fedora 26, and should improve some more for F-26 goes GA. I was getting around 8 MBps on F-25, on F-26 with the same SD card I can get around 22-24. Most of these changes won't be coming to F-25 as it's very fiddly and time consuming to ensure a clean upgrade path so I'll be focusing on F-26 in that regard. Peter > It's not logging anything unusual, just normal trafiic. > But following your suggestion I checked this card in my Lenovo W541 running > F25. I've got average write speed of around 7MB/s. > When I sent the same file (2.4 GiB zip) to my PI, and it nearly killed it - > 1.5 core constantly occupied by system, rest is blocked by IO waits. But > write speed wasn't so much worse: 4.1 MiB/s. > Just for curiosity, I wrote the same file onto USB stick attached to my PI - > this time it was slower (3.2 MiB/s), but system seemed to be more > responsive. > So writing is CPU intensive and that makes me wonder what is use_spi_crc > option responsible for in mmc_core kernel module and how to check it's > current value. > > After quick look into module's code I see it is supposed to do some data > validation with crc which I think may lead to lots of CPU intensive > operations in kernel mode ? > How do I check "use_spi_crc" current value? I couldn't find any obvious > files in /proc or /sys filesystems. > If it's value is "true" than how do I set it to false? Is proper > /etc/modprobe.d file entry sufficient or should I play with kernel > parameters at startup since it is responsible for accessing root filesystem > ? > > regards, > marcinek > > 2017-05-08 14:55 GMT+02:00 Richard Ryniker <ryniker@xxxxxxxxxxxx>: >> >> If the slowdown is due to log writes, what is written into your journal? >> >> It may be awkward to access the journal using the RPi, but move the SD >> card to another Fedora system (many laptops have flash card readers built >> in, or use a USB device) and a "smoking gun" may be obvious. The journal >> format does not depend on machine architecture. Use the --directory= >> argument for journalctl. > > > > > _______________________________________________ > arm mailing list -- arm@xxxxxxxxxxxxxxxxxxxxxxx > To unsubscribe send an email to arm-leave@xxxxxxxxxxxxxxxxxxxxxxx > _______________________________________________ arm mailing list -- arm@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to arm-leave@xxxxxxxxxxxxxxxxxxxxxxx
