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Kernel source tree for Raspberry Pi-provided kernel builds. Issues unrelated to the linux kernel should be posted on the community forum at https://forums.raspberrypi.com/
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Please enable CONFIG_BLK_DEV_IO_TRACE #702

Closed vpelletier closed 7 years ago

vpelletier commented 9 years ago

Block io tracing feature would help reduce SD wear by being able to know where writes happen and why (=what processes cause these writes). This is especially useful to see how often a given block is written to, such as fs superblocks.

popcornmix commented 9 years ago

I think this needs some testing. Enabling this option also enables:

CONFIG_TRACEPOINTS=y
CONFIG_NOP_TRACER=y
CONFIG_EVENT_TRACING=y
CONFIG_CONTEXT_SWITCH_TRACER=y
CONFIG_TRACING=y
CONFIG_GENERIC_TRACER=y
CONFIG_BINARY_PRINTF=y

I used to enable more tracing options in the kernel until I discovered it cost us about 10% in performance. If you want this in you'll need to build the kernel with it enabled and provide some evidence that doesn't cause any performance regressions (e.g. measure "free -h" and perhaps nbench before and after the change).

vpelletier commented 9 years ago

Sadly, I'm not near that Pi anymore (and don't want to take the risk of it not booting) and don't have aniother at hand, so I cannot run tests. It's an interesting point nevertheless, that enabling debug/trace features could slow down execution. The load from my use is very light so I could easily live with the overhead.

Ruffio commented 8 years ago

@vpelletier has this issue been resolved? If yes, please close this issue. Thanks.

JamesH65 commented 7 years ago

Closing due to lack of activity. Reopen if you feel this issue is still relevant.