On 01/22/2018 04:17 PM, Sebastian Ochmann wrote: > Hello, > > I attached to the ffmpeg-mux process for a little while and pasted the > result here: > > https://urldefense.proofpoint.com/v2/url?u=https-3A__pastebin.com_XHaMLX8z&d=DwIDaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=9QPtTAxcitoznaWRKKHoEQ&m=IkofqwZ_S5C0_qAXjt4EQae-mVE09Ir8zmSbuGqXaCs&s=1nw7xUkEoQF7MgYOlZ8iAA9U0UsRQObH1Z4VLqx8IF8&e= > > > Can you help me with interpreting this result? If you'd like me to run > strace with specific options, please let me know. This is a level of > debugging I'm not dealing with on a daily basis. :) > Going to guess it's these sequences: lseek(3, 1302012898, SEEK_SET) = 1302012898 write(3, "\37C\266u\1\377\377\377\377\377\377\377\277\204|\271\347J\347\203\3@\0\243CY\202\0\0\0!\21"..., 262144) = 262144 write(3, "\310\22\323g7J#h\351\0\323\270\f\206\5\207(.\232\246\27\371/\376\341\0\0\200\th\3\37"..., 262144) = 262144 write(3, "\225*\245<8N\32\263\237k\331]\313\215\301\366$\7\216\0349\302AS\201\302\307T\361\365\3375"..., 262144) = 262144 write(3, "\272e\37\255\250\24n\235\341E\272Me\36'\345W\353\2337K.n\367\264\\\370\307\341_\206|"..., 262144) = 262144 write(3, "iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii"..., 53271) = 53271 lseek(3, 1302012902, SEEK_SET) = 1302012902 write(3, "\1\0\0\0\0\20\320\v", 8) = 8 lseek(3, 1303114745, SEEK_SET) = 1303114745 It's seeking, writing, then jumping back and updating what had been written before. That's going to hit the stable page writing code in btrfs that I had mentioned earlier. At Facebook, we've been experimenting with fixes for this that are limited to O_APPEND slowly growing log files. Let me think harder... -chris -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
