Sorry for replying to my email but I forgot to set a subject while doing git send-email. So at least set it now. Honza On Wed 16-06-10 18:33:49, Jan Kara wrote: > Hello, > > here is the fourth version of the writeback livelock avoidance patches > for data integrity writes. To quickly summarize the idea: we tag dirty > pages at the beginning of write_cache_pages with a new TOWRITE tag and > then write only tagged pages to avoid parallel writers to livelock us. > See changelogs of the patches for more details. > I have tested the patches with fsx and a test program I wrote which > checks that if we crash after fsync, the data is indeed on disk. > If there are no more concerns, can these patches get merged? > > Honza > > Changes since last version: > - tagging function was changed to stop after given amount of pages to > avoid keeping tree_lock and irqs disabled for too long > - changed names and updated comments as Andrew suggested > - measured memory impact and reported it in the changelog > > Things suggested but not changed (I want to avoid going in circles ;): > - use tagging also for WB_SYNC_NONE writeback - there's problem with an > interaction with wbc->nr_to_write. If we tag all dirty pages, we can > spend too much time tagging when we write only a few pages in the end > because of nr_to_write. If we tag only say nr_to_write pages, we may > not have enough pages tagged because some pages are written out by > someone else and so we would have to restart and tagging would become > essentially useless. So my option is - switch to tagging for WB_SYNC_NONE > writeback if we can get rid of nr_to_write. But that's a story for > a different patch set. > - implement function for clearing several tags (TOWRITE, DIRTY) at once > - IMHO not worth it because we would save only conversion of page index > to radix tree offsets. The rest would have to be separate anyways. And > the interface would be incosistent as well... > - use __lookup_tag to implement radix_tree_range_tag_if_tagged - doesn't > quite work because __lookup_tag returns only leaf nodes so we'd have to > implement tree traversal anyways to tag also internal nodes. > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
