[Qemu-devel] qemu io path
hi dear all. im searching for qemu io (storage) stack. i searched a lot but just found some slides which does not present so much.is there any text explanation or article or blog post which describes precisely qemu io stack? I would be grateful if you provide something for me.and have some question hope you answer them. before ask my question its worth noting that i have an excellent background about Linux io stack and read qemu source code for main iothread and know about qemu structure, guest os ,... I read [hw/block/virtio-blk.c] and started fromvirtio_blk_handle_output function and trace it until reached toio_submit! that great we reached host kernel libaio syscalls.but what made me confuesd, is what and where and when th stuffs fordoing a typical io request from a typical guest os starts?! now here is my questions: 1- i wanna know codes which doing so.(start an io request untilio_submit get called) 2- can you give me th exact path of an io request from app in guest osthrough qemu until get to real disk? 3- does it possible to determin bellow featers for an io request:a- which guest os sent this io request?b- address which io request points to?c- request type read/write?d- request size? 4- if there is multiple disks in system, where it is define iorequest is corresponds to which disk?thank a lot -- Best Regrads Ata Fatahi Baarzi <http://ce.sharif.edu/~fatahibarzi>
[Qemu-devel] qemu io path
hi dear all. im searching for qemu io (storage) stack. i searched a lot but just found some slides which does not present so much. is there any text explanation or article or blog post which describes precisely qemu io stack? I would be grateful if you provide something for me. and have some question hope you answer them. before ask my question its worth noting that i have an excellent background about Linux io stack and read qemu source code for main io thread and know about qemu structure, guest os ,... i read [hw/block/virtio-blk.c] and started from virtio_blk_handle_output function and trace it until reached to io_submit! that great we reached host kernel libaio syscalls. but what made me confuesd, is what and where and when th stuffs for doing a typical io request from a typical guest os starts?! now here is my questions: 1- i wanna know codes which doing so.(start an io request until io_submit get called) 2- can you give me th exact path of an io request from app in guest os through qemu until get to real disk? 3- does it possible to determin bellow featers for an io request: a- which guest os sent this io request? b- address which io request points to? c- request type read/write? d- request size? e- if there is multiple disks in system, where it is define io request is corresponds to which disk? thank a lot -- Best Regrads Ata Fatahi Baarzi <http://ce.sharif.edu/~fatahibarzi>
[Qemu-devel] other cahpters about qemu
hi all i found a chapter named chapter qemu detailed study hers <https://lists.gnu.org/archive/html/qemu-devel/2011-04/pdfhC5rVdz7U8.pdf>. how can i find ther chapters? -- Best Regrads Ata Fatahi Baarzi <http://ce.sharif.edu/~fatahibarzi>
[Qemu-devel] qemu io stack code approach
hi all I recently pursued Linux IO stack and dove into kernel source code. that is when a user programm calls read or write syscall some functions will be called to finally make a io request and send it to device drivers and compelete io request. in this path which is known as Life of IO request i placed some printks in linux kernel and compile and install it then i can see IO requests information in /var/log/syslog. i totally used This good Post <https://scaryreasoner.wordpress.com/2013/09/14/the-life-of-io-in-the-linux-kernel/> which done for linux kernel. know i wanna do some thing like that in qemu to answer these too important questions: 1- what is path of a IO request from a guest os to host os and finally disk? (both siurce code approach and io stack approach) 2- how qemu determines an IO request is corresponds to which guest os?(if its feasible) -- Best Rega ​r​ ds Ata Fatahi Baarzi <http://ce.sharif.edu/~fatahibarzi>
