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nvs: Fix page selection algo to consider free entry counts as well

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Current page selection algorithm selects a page for compaction based on just erased counts
and gives up when it does not find any page with erased count greater than 0. This is
problematic since the current allocation procedure skips the active page if there is not
enough room for the item in that page leaving free chunks on the pages. This change modifies
the algorithm to consider both erased as well as free counts on the candidate pages.

Closes TW<20297>
This commit is contained in:
Sagar Bijwe 2018-04-13 14:49:05 +05:30
parent c876ab390b
commit 7e79471ece
2 changed files with 32 additions and 9 deletions
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20
components/nvs_flash/src/nvs_pagemanager.cpp
View file

@ -125,17 +125,18 @@ esp_err_t PageManager::requestNewPage()
}
// find the page with the higest number of erased items
TPageListIterator maxErasedItemsPageIt;
size_t maxErasedItems = 0;
TPageListIterator maxUnusedItemsPageIt;
size_t maxUnusedItems = 0;
for (auto it = begin(); it != end(); ++it) {
auto erased = it->getErasedEntryCount();
if (erased > maxErasedItems) {
maxErasedItemsPageIt = it;
maxErasedItems = erased;
auto unused = Page::ENTRY_COUNT - it->getUsedEntryCount();
if (unused > maxUnusedItems) {
maxUnusedItemsPageIt = it;
maxUnusedItems = unused;
}
}
if (maxErasedItems == 0) {
if (maxUnusedItems == 0) {
return ESP_ERR_NVS_NOT_ENOUGH_SPACE;
}
@ -146,7 +147,8 @@ esp_err_t PageManager::requestNewPage()
Page* newPage = &mPageList.back();
Page* erasedPage = maxErasedItemsPageIt;
Page* erasedPage = maxUnusedItemsPageIt;
#ifndef NDEBUG
size_t usedEntries = erasedPage->getUsedEntryCount();
#endif
@ -172,7 +174,7 @@ esp_err_t PageManager::requestNewPage()
assert(usedEntries == newPage->getUsedEntryCount());
#endif
mPageList.erase(maxErasedItemsPageIt);
mPageList.erase(maxUnusedItemsPageIt);
mFreePageList.push_back(erasedPage);
return ESP_OK;

21
components/nvs_flash/test_nvs_host/test_nvs.cpp
View file

@ -1246,6 +1246,27 @@ TEST_CASE("multiple partitions access check", "[nvs]")
CHECK(v2 == 0xcafebabe);
}
TEST_CASE("nvs page selection takes into account free entries also not just erased entries", "[nvs]")
{
const size_t blob_size = Page::BLOB_MAX_SIZE;
uint8_t blob[blob_size] = {0};
SpiFlashEmulator emu(3);
TEST_ESP_OK( nvs_flash_init_custom(NVS_DEFAULT_PART_NAME, 0, 3) );
nvs_handle handle;
TEST_ESP_OK( nvs_open("test", NVS_READWRITE, &handle) );
// Fill first page
TEST_ESP_OK( nvs_set_blob(handle, "1a", blob, blob_size/3) );
TEST_ESP_OK( nvs_set_blob(handle, "1b", blob, blob_size) );
// Fill second page
TEST_ESP_OK( nvs_set_blob(handle, "2a", blob, blob_size) );
TEST_ESP_OK( nvs_set_blob(handle, "2b", blob, blob_size) );
// The item below should be able to fit the first page.
TEST_ESP_OK( nvs_set_blob(handle, "3a", blob, 4) );
TEST_ESP_OK( nvs_commit(handle) );
nvs_close(handle);
}
TEST_CASE("dump all performance data", "[nvs]")
{
std::cout << "====================" << std::endl << "Dumping benchmarks" << std::endl;