Hello, Tao.
On Tue, 08 Sep 2026 18:01:42 +0800, Tao Cui wrote:
quoted hunk ↗ jump to hunk
+ if (flags & IOCOST_COST_F_MERGE) {
+ base = 0;
+ goto out;
Please advance the stream position for merged bios too. With 4K IOs, a new
request at sector S sets expected to S+8. A merged bio at S+8 leaves it
there, so the next new request at S+16 is priced random.
quoted hunk ↗ jump to hunk
+ s = bpf_map_lookup_elem(&stream_tab, &iocg_id);
+ if (!s)
+ return seqio + RU(nbytes, IOC_PAGE_SIZE) * page;
Once the 64-entry map fills, every new cgroup receives sequential prices,
including for random IO. Please note this limitation in the example.
Thanks.
--
tejun