On Fri, May 10, 2024 at 11:06:14AM +0800, Zhaoyang Huang wrote: > On Thu, May 9, 2024 at 8:40 PM Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: > > > > > + unsigned long budgt = inode->i_sb->s_bdev ? > > > + blk_throttle_budgt(inode->i_sb->s_bdev) : 0; > > > > The readahead code is used for all file systems, you can't just call > > into block layer code here. > > > ok. I would like to know any suggestions on introducing throttle > budget control into readahead which actually works as a negative > feedback path. IMO, negative feedback is a good methodology which has > been used in scheduler(EAS) and thermal control(IPA) and > memory(MGLRU). I would like to suggest to have a try on have it work > cross the boundary of memory and block layer. > > vfs_read / page fault > | > readahead <---------| > | | > aops->readpages | > | | > block_layer------------ what you could do is have blk-throttle fail bios that are tagged as readahead if we've hit the threshold?
