Messages in this thread | | | From | Yafang Shao <> | Date | Thu, 30 Sep 2021 20:53:27 +0800 | Subject | Re: [PATCH 4/5] kernel: increase the size of kthread's comm |
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On Thu, Sep 30, 2021 at 2:20 AM Kees Cook <keescook@chromium.org> wrote: > > On Wed, Sep 29, 2021 at 11:50:35AM +0000, Yafang Shao wrote: > > This patch increases the size of ktread's comm from 16 to 24, which is > > the same with workqueue's, to improve this situation. After this cahnge, > > [...] > > Because there're only a few of kthreads, so it won't increase too much > > memory. > > Even without the performance impact changes, the math here doesn't hold > either, since using kmalloc means there are slabs being allocated to hold > the task "comm"s now (which comes with overhead), and every task added > a pointer to those 16 bytes (i.e. 8 more bytes on 64-bit systems). So > this change, even if there was 0 overhead in using slabs, would be > identical to having just raised TASK_COMM_LEN to 24. 8 byte pointer, > 16 byte allocation == 24 bytes. >
Right, thanks for the explanation. I missed the pointer before.
What about reusing the kthread_data() to store the the comm if the kthread is not a kworker?
struct kthread { ... void *data; // reuse this pointer ... }
The logic will be something as follows,
if (kthread_is_kworker) { store_worker_desc_into_kthread_data(); // already did in the kernel } else { store_comm_into_kthread_data(); // that is what we should change }
And then we modify the proc_task_name() correspondingly.
-- Thanks Yafang
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