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Message-ID: <4F4669B1.4020306@tu-ilmenau.de> Date: Thu, 23 Feb 2012 17:30:41 +0100 From: Stephan Bärwolf <stephan.baerwolf@...ilmenau.de> To: linux-kernel@...r.kernel.org CC: Linus Torvalds <torvalds@...ux-foundation.org>, Michael Buesch <mb@...sch.de>, Chris Wilson <chris@...is-wilson.co.uk>, Alex Deucher <alexdeucher@...il.com>, Dave Airlie <airlied@...hat.com> Subject: responsiveness: newer kernels causing lagging and blocking Under various conditions linux since 2.6.39-rc1 laggs and blocks enormously the whole system. (For example while starting "winecfg" (on a thinkpad X220) and parallel moving the mousecursor you can observe a periodic blocking for some seconds) After bisecting a little while, commit "4819d2e4310796c4e9eef674499af9b9caf36b5a" (" drm: Retry i2c transfer of EDID block after failure ") seems to be responsible. Because function "drm_do_probe_ddc_edid" loops trying "i2c_transfer" it consumes a lot of time during errors. Reverting or changing "retries" from 5 to 1 extremly minimizes the problem to "not perceptible". It seems the locking within "i2c_transfer" slows everything down. So maybe it is possible to yield() before calling it? regards Stephan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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