【linux对进程的读写量统计】struct task_struct有struct task_io_accounting ioac;
struct task_io_accounting {
#ifdef CONFIG_TASK_XACCT
/* bytes read */
u64 rchar;
/*bytes written */
u64 wchar;
/* # of read syscalls */
u64 syscr;
/* # of write syscalls */
u64 syscw;
#endif /* CONFIG_TASK_XACCT */#ifdef CONFIG_TASK_IO_ACCOUNTING
/*
* The number of bytes which this task has caused to be read from
* storage.
*/
u64 read_bytes;
/*
* The number of bytes which this task has caused, or shall cause to be
* written to disk.
*/
u64 write_bytes;
/*
* A task can cause "negative" IO too.If this task truncates some
* dirty pagecache, some IO which another task has been accounted for
* (in its write_bytes) will not be happening.We _could_ just
* subtract that from the truncating task's write_bytes, but there is
* information loss in doing that.
*/
u64 cancelled_write_bytes;
#endif /* CONFIG_TASK_IO_ACCOUNTING */
};
每个task_struct内嵌的write_bytes，统计是该进程写内存的字节数，这个写的，当前时刻可能还在内存里面，不一定写到磁盘里了。
void __set_page_dirty(struct page *page, struct address_space *mapping,
int warn)
{
unsigned long flags;
xa_lock_irqsave(&mapping->i_pages, flags);
if (page->mapping) {/* Race with truncate? */
WARN_ON_ONCE(warn && !PageUptodate(page));
account_page_dirtied(page, mapping);
__xa_set_mark(&mapping->i_pages, page_index(page),
PAGECACHE_TAG_DIRTY);
}
xa_unlock_irqrestore(&mapping->i_pages, flags);
}static void account_page_dirtied(struct page *page,
struct address_space *mapping)
{
struct inode *inode = mapping->host;
trace_writeback_dirty_page(page, mapping);
if (mapping_can_writeback(mapping)) {
struct bdi_writeback *wb;
inode_attach_wb(inode, page);
wb = inode_to_wb(inode);
__inc_lruvec_page_state(page, NR_FILE_DIRTY);
__inc_zone_page_state(page, NR_ZONE_WRITE_PENDING);
__inc_node_page_state(page, NR_DIRTIED);
inc_wb_stat(wb, WB_RECLAIMABLE);
inc_wb_stat(wb, WB_DIRTIED);
task_io_account_write(PAGE_SIZE);
current->nr_dirtied++;
__this_cpu_inc(bdp_ratelimits);
mem_cgroup_track_foreign_dirty(page, wb);
}
}static inline void task_io_account_write(size_t bytes)
{
current->ioac.write_bytes += bytes;
}
