diff options
Diffstat (limited to 'Documentation/vm')
| -rw-r--r-- | Documentation/vm/hmm.rst | 20 | ||||
| -rw-r--r-- | Documentation/vm/zswap.rst | 13 |
2 files changed, 23 insertions, 10 deletions
diff --git a/Documentation/vm/hmm.rst b/Documentation/vm/hmm.rst index 893a8ba0e9fe..95fec5968362 100644 --- a/Documentation/vm/hmm.rst +++ b/Documentation/vm/hmm.rst @@ -149,14 +149,14 @@ CPU page table into a device page table; HMM helps keep both synchronized. A device driver that wants to mirror a process address space must start with the registration of a mmu_interval_notifier:: - mni->ops = &driver_ops; - int mmu_interval_notifier_insert(struct mmu_interval_notifier *mni, - unsigned long start, unsigned long length, - struct mm_struct *mm); + int mmu_interval_notifier_insert(struct mmu_interval_notifier *interval_sub, + struct mm_struct *mm, unsigned long start, + unsigned long length, + const struct mmu_interval_notifier_ops *ops); -During the driver_ops->invalidate() callback the device driver must perform -the update action to the range (mark range read only, or fully unmap, -etc.). The device must complete the update before the driver callback returns. +During the ops->invalidate() callback the device driver must perform the +update action to the range (mark range read only, or fully unmap, etc.). The +device must complete the update before the driver callback returns. When the device driver wants to populate a range of virtual addresses, it can use:: @@ -183,7 +183,7 @@ The usage pattern is:: struct hmm_range range; ... - range.notifier = &mni; + range.notifier = &interval_sub; range.start = ...; range.end = ...; range.pfns = ...; @@ -191,11 +191,11 @@ The usage pattern is:: range.values = ...; range.pfn_shift = ...; - if (!mmget_not_zero(mni->notifier.mm)) + if (!mmget_not_zero(interval_sub->notifier.mm)) return -EFAULT; again: - range.notifier_seq = mmu_interval_read_begin(&mni); + range.notifier_seq = mmu_interval_read_begin(&interval_sub); down_read(&mm->mmap_sem); ret = hmm_range_fault(&range, HMM_RANGE_SNAPSHOT); if (ret) { diff --git a/Documentation/vm/zswap.rst b/Documentation/vm/zswap.rst index 1444ecd40911..61f6185188cd 100644 --- a/Documentation/vm/zswap.rst +++ b/Documentation/vm/zswap.rst @@ -130,6 +130,19 @@ checking for the same-value filled pages during store operation. However, the existing pages which are marked as same-value filled pages remain stored unchanged in zswap until they are either loaded or invalidated. +To prevent zswap from shrinking pool when zswap is full and there's a high +pressure on swap (this will result in flipping pages in and out zswap pool +without any real benefit but with a performance drop for the system), a +special parameter has been introduced to implement a sort of hysteresis to +refuse taking pages into zswap pool until it has sufficient space if the limit +has been hit. To set the threshold at which zswap would start accepting pages +again after it became full, use the sysfs ``accept_threhsold_percent`` +attribute, e. g.:: + + echo 80 > /sys/module/zswap/parameters/accept_threhsold_percent + +Setting this parameter to 100 will disable the hysteresis. + A debugfs interface is provided for various statistic about pool size, number of pages stored, same-value filled pages and various counters for the reasons pages are rejected. |