Dave Hansen <[email protected]> writes: > On 02/17/2014 06:33 AM, Peter Zijlstra wrote: >> Then write the PERF_RECORD_DATA structure into the normal ring-buffer >> location; set data_offset to point to the first page boundary, data_size >> to 1mb. >> >> Then frob things such that perf_mmap_to_page() for the next 1mb of pages >> points to your buffer pages and wipe the page-table entries. > > Wouldn't we have to teach a ton of code how to be IRQ safe for this to > work? Just step one: how do we go modifying page tables safely from an > interrupt? mm->page_table_lock is a plain non-irq spinlock.
Yes, this does look more than just tricky even if we move the bulk of interrupt code to an irq_work. Peter, are you quite sure this is what we want to do just for exporting trace buffers to userspace? Regards, -- Alex -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
