Messages in this thread | | | From | Oscar Salvador <> | Subject | [PATCH 0/5] Refactor node_states_check_changes_online/offline | Date | Wed, 19 Sep 2018 12:08:14 +0200 |
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From: Oscar Salvador <osalvador@suse.de>
This patchset refactors/clean ups node_states_check_changes_online/offline functions together with node_states_set/clear_node.
The main reason behind this patchset is that currently, these functions are suboptimal and confusing.
For example, they contain wrong statements like:
if (N_MEMORY == N_NORMAL_MEMORY) if (N_MEMORY =! N_NORMAL_MEMORY) if (N_MEMORY != N_HIGH_MEMORY) if (N_MEMORY == N_HIGH_MEMORY)
These comparasions are wrong, as N_MEMORY will never be equal to either N_NORMAL_MEMORY or N_HIGH_MEMORY. Although the statements do not "affect" the flow because in the way they are placed, they are completely wrong and confusing.
I caught another misuse of this in [1].
Another thing that this patchset addresses is the fact that some functions get called twice, or even unconditionally, without any need.
Examples of this are:
- node_states_set_node()->node_set_state(node, N_MEMORY)
* node_states_set_node() gets called whenever we online pages, so we end up calling node_set_state(node, N_MEMORY) everytime. To avoid this, we should check if the node is already in node_state[N_MEMORY].
- node_states_set_node()->node_set_state(node, N_HIGH_MEMORY)
* On !CONFIG_HIGH_MEMORY, N_HIGH_MEMORY == N_NORMAL_MEMORY, but the current code sets: status_change_nid_high = status_change_nid_normal This means that we will call node_set_state(node, N_NORMAL_MEMORY) twice. The fix here is to set status_change_nid_normal = -1 on such systems, so we skip the second call.
[1] https://patchwork.kernel.org/patch/10579155/
Oscar Salvador (5): mm/memory_hotplug: Spare unnecessary calls to node_set_state mm/memory_hotplug: Avoid node_set/clear_state(N_HIGH_MEMORY) when !CONFIG_HIGHMEM mm/memory_hotplug: Tidy up node_states_clear_node mm/memory_hotplug: Simplify node_states_check_changes_online mm/memory_hotplug: Clean up node_states_check_changes_offline
mm/memory_hotplug.c | 153 +++++++++++++++++++++------------------------------- 1 file changed, 60 insertions(+), 93 deletions(-)
-- 2.13.6
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